Camp Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Observatory clear sky chart from 2005-11-05 to 2017-10-31.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
26%
15052
14%
47366
7%
15021
35%
15021
15%
33430

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
11%
720
12%
2506
5%
716
20%
716
7%
1869
January16th to endNight
12%
768
12%
2620
3%
768
23%
768
8%
1956
February1st to 15thNight
5%
704
9%
2266
0%
701
15%
701
6%
1788
February16th to endNight
13%
631
14%
1893
5%
631
24%
631
8%
1443
March1st to 15thNight
13%
720
12%
2142
5%
720
23%
720
10%
1628
March16th to endNight
20%
768
18%
2001
7%
768
30%
768
15%
1464
April1st to 15thNight
16%
718
12%
1796
2%
718
22%
718
14%
1383
April16th to endNight
25%
690
15%
1770
4%
690
32%
690
21%
1241
May1st to 15thNight
28%
439
16%
1519
10%
439
36%
439
15%
1044
May16th to endNight
36%
374
14%
1497
10%
374
46%
374
17%
962
June1st to 15thNight
35%
360
12%
1440
11%
360
44%
360
14%
942
June16th to endNight
48%
360
11%
1440
12%
360
56%
360
24%
832
July1st to 15thNight
50%
340
11%
1360
13%
340
56%
340
23%
796
July16th to endNight
55%
376
14%
1418
15%
354
60%
354
24%
834
August1st to 15thNight
49%
487
15%
1558
9%
485
55%
485
26%
964
August16th to endNight
54%
764
18%
1910
9%
764
56%
764
33%
1257
September1st to 15thNight
44%
720
18%
1800
8%
720
49%
720
29%
1204
September16th to endNight
47%
717
24%
1958
16%
717
52%
717
31%
1227
October1st to 15thNight
34%
720
18%
2132
11%
720
42%
720
20%
1454
October16th to endNight
21%
768
12%
2404
6%
768
30%
768
13%
1716
November1st to 15thNight
25%
700
16%
2277
9%
700
34%
700
15%
1585
November16th to endNight
21%
720
15%
2451
9%
720
31%
720
12%
1742
December1st to 15thNight
15%
720
9%
2520
3%
720
24%
720
7%
1954
December16th to endNight
11%
768
9%
2688
2%
768
20%
768
5%
2145

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
14%9%47%6%35%5%5%7%30%
48390
Night
13%8%47%6%35%5%5%7%33%
47536
Cloud CoverDay
14%9%47%6%35%5%5%7%30%
48399
Night
13%8%47%6%35%5%5%7%33%
47542
TransparencyDay
51%7%11%18%10%1
48078
Night
49%7%12%19%10%1
47366
SeeingDay
20%18%27%18%10%4
5849
Night
22%20%25%21%8%1
15053

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
9%9%5%10%9%46%5%5%7%25%
1432
16th to endDay
9%10%6%11%9%5%7%5%5%6%22%
1602
February1st to 15thDay
12%11%7%10%10%45%5%5%5%21%
1595
16th to endDay
12%11%5%10%8%45%5%45%26%
1580
March1st to 15thDay
14%12%5%8%7%25%45%7%26%
1807
16th to endDay
14%12%5%6%43435%5%33%
2222
April1st to 15thDay
15%11%5%7%6%34345%32%
2152
16th to endDay
16%9%36%5%34446%36%
2188
May1st to 15thDay
19%10%37%5%34445%31%
2442
16th to endDay
14%7%37%6%36%5%5%8%32%
2618
June1st to 15thDay
20%7%27%5%26%5%5%8%28%
2520
16th to endDay
14%7%27%6%46%5%6%9%28%
2520
July1st to 15thDay
11%6%37%7%46%6%6%8%30%
2520
16th to endDay
11%6%37%6%47%6%6%9%31%
2654
August1st to 15thDay
12%6%38%6%45%6%6%8%29%
2376
16th to endDay
14%5%25%5%35%5%7%8%35%
2292
September1st to 15thDay
15%6%36%5%345%5%6%37%
2160
16th to endDay
13%5%2442445%7%44%
2001
October1st to 15thDay
16%10%36%5%33446%35%
1827
16th to endDay
18%11%27%5%245%5%6%28%
1818
November1st to 15thDay
15%11%35%5%35%5%46%33%
1581
16th to endDay
13%10%46%7%35%6%46%30%
1507
December1st to 15thDay
13%16%6%11%7%3445%5%22%
1440
16th to endDay
14%15%7%10%6%35%5%5%6%18%
1536
January1st to 15thNight
11%10%5%11%8%346%6%8%23%
2506
16th to endNight
10%9%6%9%8%46%5%6%7%25%
2620
February1st to 15thNight
11%11%6%9%10%36%5%6%7%21%
2265
16th to endNight
12%9%7%9%7%46%6%5%6%24%
1893
March1st to 15thNight
15%8%49%7%45%5%5%5%28%
2129
16th to endNight
15%9%47%6%2445%7%33%
2001
April1st to 15thNight
15%11%36%6%35%45%5%30%
1796
16th to endNight
17%8%35%424346%38%
1770
May1st to 15thNight
18%10%45%43335%5%36%
1519
16th to endNight
13%5%25%5%35%46%8%38%
1495
June1st to 15thNight
20%6%344245%47%36%
1440
16th to endNight
10%415%42447%11%43%
1440
July1st to 15thNight
9%4245%27%6%6%7%44%
1440
16th to endNight
11%4245%245%6%8%44%
1514
August1st to 15thNight
9%4245%35%5%6%7%44%
1568
16th to endNight
12%5%25%42345%7%46%
1910
September1st to 15thNight
14%5%24435%45%7%45%
1800
16th to endNight
11%4145%245%46%49%
1958
October1st to 15thNight
18%7%26%42345%5%39%
2132
16th to endNight
19%9%25%43445%8%30%
2404
November1st to 15thNight
14%11%36%5%3445%6%34%
2277
16th to endNight
13%9%5%7%6%35%46%5%31%
2451
December1st to 15thNight
15%12%5%9%6%35%5%5%6%23%
2520
16th to endNight
14%13%6%9%7%36%5%5%6%19%
2688

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
9%9%6%10%8%5%6%5%6%7%25%
1432
16th to endDay
9%10%6%11%9%5%6%5%6%6%23%
1602
February1st to 15thDay
11%11%7%11%9%5%5%5%5%5%21%
1595
16th to endDay
11%11%5%10%7%35%6%45%26%
1580
March1st to 15thDay
15%12%6%7%6%35%35%7%26%
1817
16th to endDay
14%10%5%7%5%34445%33%
2221
April1st to 15thDay
15%11%5%7%6%34335%33%
2152
16th to endDay
15%11%35%5%34346%35%
2188
May1st to 15thDay
18%11%28%5%25%446%30%
2442
16th to endDay
15%7%37%6%36%5%6%7%31%
2618
June1st to 15thDay
20%7%37%5%35%5%5%8%28%
2520
16th to endDay
15%7%38%6%45%6%6%9%27%
2520
July1st to 15thDay
11%6%27%8%46%6%6%9%29%
2520
16th to endDay
11%6%27%6%47%5%6%8%31%
2654
August1st to 15thDay
12%6%38%8%46%5%6%8%29%
2376
16th to endDay
13%6%25%6%35%6%7%8%35%
2292
September1st to 15thDay
14%6%26%5%35%5%5%6%37%
2160
16th to endDay
13%6%244245%46%45%
2001
October1st to 15thDay
15%9%45%5%23446%36%
1827
16th to endDay
18%11%46%6%335%5%5%28%
1818
November1st to 15thDay
15%12%26%43446%6%33%
1581
16th to endDay
12%11%46%6%446%46%30%
1507
December1st to 15thDay
13%14%7%10%6%35%45%5%22%
1440
16th to endDay
13%16%7%11%7%26%5%5%6%17%
1536
January1st to 15thNight
11%11%410%8%45%6%6%8%23%
2506
16th to endNight
10%9%5%10%8%46%5%6%7%25%
2620
February1st to 15thNight
10%11%6%10%9%46%6%5%6%21%
2258
16th to endNight
12%8%6%9%8%45%5%6%6%25%
1893
March1st to 15thNight
15%9%5%9%7%35%5%5%5%28%
2142
16th to endNight
14%9%49%42435%7%33%
2001
April1st to 15thNight
14%12%47%5%3445%6%30%
1796
16th to endNight
17%7%36%324447%38%
1770
May1st to 15thNight
18%10%27%424346%35%
1519
16th to endNight
13%6%26%445%6%5%8%38%
1495
June1st to 15thNight
19%7%245%2445%6%36%
1440
16th to endNight
10%4244245%6%11%43%
1440
July1st to 15thNight
9%4245%26%5%7%7%43%
1440
16th to endNight
11%4235%246%5%9%44%
1514
August1st to 15thNight
9%425%5%345%6%7%44%
1568
16th to endNight
12%5%15%434446%46%
1910
September1st to 15thNight
13%5%2343445%7%44%
1800
16th to endNight
10%5%135%24447%48%
1958
October1st to 15thNight
18%7%25%42435%6%39%
2132
16th to endNight
18%9%26%5%24448%31%
2404
November1st to 15thNight
13%11%35%5%2445%6%34%
2277
16th to endNight
12%10%5%7%6%35%5%46%31%
2451
December1st to 15thNight
14%12%5%10%6%45%5%5%6%23%
2520
16th to endNight
14%13%6%10%6%45%5%5%7%19%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
56%7%11%16%6%
1433
16th to endDay
59%9%10%14%6%1
1602
February1st to 15thDay
63%7%8%13%6%
1598
16th to endDay
57%6%9%16%8%
1580
March1st to 15thDay
57%5%12%16%7%1
1817
16th to endDay
52%5%7%16%14%2
2222
April1st to 15thDay
53%48%19%11%1
2152
16th to endDay
49%48%20%14%2
2188
May1st to 15thDay
54%6%7%19%10%1
2442
16th to endDay
49%8%13%18%9%
2622
June1st to 15thDay
53%6%12%17%8%
2520
16th to endDay
51%7%14%15%9%
2520
July1st to 15thDay
48%9%12%19%9%
2371
16th to endDay
47%8%14%19%9%
2487
August1st to 15thDay
49%9%12%18%9%
2362
16th to endDay
42%8%12%23%11%
2292
September1st to 15thDay
45%7%11%21%13%
2160
16th to endDay
37%5%9%25%19%1
2001
October1st to 15thDay
48%6%8%21%13%1
1827
16th to endDay
54%7%12%16%8%
1818
November1st to 15thDay
49%7%12%17%10%1
1581
16th to endDay
52%7%12%16%10%1
1507
December1st to 15thDay
63%6%11%12%5%
1440
16th to endDay
65%7%11%11%3
1536
January1st to 15thNight
55%8%11%13%9%1
2506
16th to endNight
54%8%10%15%8%1
2620
February1st to 15thNight
60%9%9%13%6%
2266
16th to endNight
56%8%10%15%8%1
1893
March1st to 15thNight
56%6%10%17%7%
2142
16th to endNight
49%6%9%18%13%2
2001
April1st to 15thNight
54%7%10%17%9%1
1796
16th to endNight
45%6%11%19%15%1
1770
May1st to 15thNight
50%5%9%18%14%1
1519
16th to endNight
43%8%14%21%10%1
1497
June1st to 15thNight
48%5%13%22%8%
1440
16th to endNight
33%8%19%27%10%
1440
July1st to 15thNight
36%8%15%26%11%1
1360
16th to endNight
35%8%17%25%11%1
1418
August1st to 15thNight
35%9%17%26%10%1
1558
16th to endNight
37%5%14%29%12%
1910
September1st to 15thNight
38%7%14%25%14%
1800
16th to endNight
34%6%11%25%20%1
1958
October1st to 15thNight
45%6%11%20%14%1
2132
16th to endNight
50%7%14%19%8%
2404
November1st to 15thNight
47%8%11%17%12%2
2277
16th to endNight
51%7%12%18%8%1
2451
December1st to 15thNight
60%8%12%13%5%
2520
16th to endNight
63%8%9%12%6%
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
25%35%18%15%6%
60
16th to endDay
30%34%25%9%
75
February1st to 15thDay
25%42%25%41
112
16th to endDay
21%31%28%15%2
239
March1st to 15thDay
28%27%27%13%3
270
16th to endDay
28%26%24%11%7%1
288
April1st to 15thDay
27%26%24%12%7%1
270
16th to endDay
21%20%29%16%6%5%
270
May1st to 15thDay
30%18%23%14%7%5%
288
16th to endDay
18%16%34%17%10%3
331
June1st to 15thDay
22%14%30%20%9%
315
16th to endDay
17%17%32%21%8%2
315
July1st to 15thDay
13%9%35%26%12%2
305
16th to endDay
12%9%33%28%12%3
326
August1st to 15thDay
12%10%27%24%16%7%
313
16th to endDay
14%8%24%25%15%12%
332
September1st to 15thDay
17%10%21%23%17%9%
315
16th to endDay
14%7%22%20%18%15%
314
October1st to 15thDay
18%14%24%22%15%4
315
16th to endDay
28%21%26%16%7%
310
November1st to 15thDay
26%15%27%17%10%1
235
16th to endDay
18%32%23%14%9%1
127
December1st to 15thDay
26%38%20%8%6%
60
16th to endDay
26%42%25%6%
64
January1st to 15thNight
23%32%29%12%2
720
16th to endNight
22%32%28%14%1
768
February1st to 15thNight
23%30%34%10%
704
16th to endNight
23%31%26%15%2
631
March1st to 15thNight
27%28%28%13%2
720
16th to endNight
25%24%23%19%5%
768
April1st to 15thNight
25%25%29%17%2
718
16th to endNight
24%19%27%16%10%1
690
May1st to 15thNight
26%14%25%24%8%
439
16th to endNight
18%10%30%26%13%1
375
June1st to 15thNight
25%10%21%29%11%
360
16th to endNight
14%6%27%38%12%
360
July1st to 15thNight
10%8%25%39%15%
340
16th to endNight
12%422%42%16%1
376
August1st to 15thNight
11%5%27%34%18%2
487
16th to endNight
16%5%18%34%22%3
764
September1st to 15thNight
17%10%23%29%16%2
720
16th to endNight
14%10%23%24%20%6%
717
October1st to 15thNight
24%15%19%24%14%1
720
16th to endNight
26%22%26%20%4
768
November1st to 15thNight
23%21%26%20%7%1
700
16th to endNight
24%24%25%18%6%1
720
December1st to 15thNight
25%30%25%14%4
720
16th to endNight
29%31%24%12%2
768
Page generated at 2017-11-01 17:23:34. Version ac04

Copyright 2017 A. Danko


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