Brass Cricket Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brass Cricket Observatory clear sky chart from 2005-11-05 to 2018-02-13.

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
28%
15451
14%
48775
7%
15420
35%
15420
16%
34560

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
14%
780
11%
2716
5%
776
22%
776
9%
2061
January16th to endNight
15%
832
10%
2879
3%
832
25%
832
10%
2172
February1st to 15thNight
11%
753
9%
2393
2%
750
19%
750
8%
1889
February16th to endNight
16%
631
13%
1893
6%
631
26%
631
11%
1444
March1st to 15thNight
14%
720
13%
2160
5%
720
24%
720
12%
1635
March16th to endNight
20%
768
19%
1995
7%
768
30%
768
17%
1451
April1st to 15thNight
20%
718
13%
1796
3%
718
25%
718
17%
1344
April16th to endNight
24%
657
16%
1737
4%
657
32%
657
21%
1218
May1st to 15thNight
24%
474
16%
1554
7%
474
35%
474
16%
1073
May16th to endNight
39%
374
12%
1497
10%
374
46%
374
15%
996
June1st to 15thNight
37%
360
11%
1440
9%
360
45%
360
15%
971
June16th to endNight
50%
360
11%
1440
12%
360
57%
360
22%
860
July1st to 15thNight
50%
340
13%
1360
15%
340
54%
340
22%
812
July16th to endNight
55%
376
15%
1418
18%
354
59%
354
23%
823
August1st to 15thNight
51%
467
15%
1538
11%
465
56%
465
27%
939
August16th to endNight
53%
764
18%
1910
9%
764
55%
764
32%
1266
September1st to 15thNight
44%
720
18%
1801
9%
720
48%
720
30%
1220
September16th to endNight
48%
717
25%
1980
17%
717
53%
717
34%
1214
October1st to 15thNight
37%
720
18%
2094
12%
720
44%
720
21%
1450
October16th to endNight
24%
768
13%
2437
7%
768
33%
768
15%
1769
November1st to 15thNight
26%
760
16%
2472
9%
760
36%
760
17%
1699
November16th to endNight
24%
780
15%
2623
8%
780
35%
780
13%
1872
December1st to 15thNight
17%
780
9%
2730
3%
780
24%
780
9%
2075
December16th to endNight
14%
832
9%
2912
3%
832
22%
832
7%
2307

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
18%8%36%5%3445%6%33%
49263
Night
18%9%36%5%34446%33%
48945
Cloud CoverDay
17%9%36%5%3445%6%32%
49273
Night
17%9%36%5%34446%33%
48950
TransparencyDay
51%5%11%19%10%1
48951
Night
51%5%11%19%10%1
48775
SeeingDay
22%16%25%20%11%3
6136
Night
23%16%26%24%8%
15452

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
15%12%48%7%46%5%5%5%24%
1552
16th to endDay
15%12%48%8%35%45%5%25%
1693
February1st to 15thDay
16%14%5%9%9%35%5%5%5%19%
1731
16th to endDay
16%13%49%7%3434426%
1580
March1st to 15thDay
20%10%5%8%5%2445%5%27%
1790
16th to endDay
18%11%46%32333436%
2226
April1st to 15thDay
20%11%37%5%3433432%
2152
16th to endDay
18%8%25%43445%6%36%
2222
May1st to 15thDay
23%8%36%5%2445%6%30%
2409
16th to endDay
19%6%3443446%7%35%
2618
June1st to 15thDay
23%6%35%5%2446%7%29%
2520
16th to endDay
18%5%35%445%6%5%8%31%
2520
July1st to 15thDay
14%6%25%5%36%6%6%9%34%
2520
16th to endDay
14%5%25%6%35%6%7%8%35%
2654
August1st to 15thDay
14%6%26%6%36%5%6%8%34%
2394
16th to endDay
14%5%244246%6%8%40%
2292
September1st to 15thDay
17%5%25%425%5%46%40%
2158
16th to endDay
15%5%13323336%51%
1980
October1st to 15thDay
20%8%26%42434437%
1863
16th to endDay
24%12%35%424435%29%
1785
November1st to 15thDay
16%10%35%5%24446%36%
1716
16th to endDay
17%10%36%42445%434%
1664
December1st to 15thDay
18%13%5%8%5%33436%26%
1560
16th to endDay
22%16%6%7%5%3443422%
1664
January1st to 15thNight
17%14%49%6%34445%25%
2716
16th to endNight
15%14%48%6%45%44425%
2879
February1st to 15thNight
16%12%5%12%8%35%445%21%
2392
16th to endNight
15%13%5%9%6%35%44426%
1893
March1st to 15thNight
21%11%47%6%3433429%
2147
16th to endNight
19%9%45%5%23345%35%
1995
April1st to 15thNight
21%10%45%425%445%31%
1796
16th to endNight
20%7%25%424446%37%
1737
May1st to 15thNight
23%8%26%323336%34%
1554
16th to endNight
17%6%246%35%5%7%7%33%
1495
June1st to 15thNight
22%7%25%425%447%33%
1440
16th to endNight
15%422425%5%6%9%42%
1440
July1st to 15thNight
13%5%25%6%25%4410%38%
1440
16th to endNight
13%3245%245%5%8%42%
1514
August1st to 15thNight
12%4245%2445%9%43%
1548
16th to endNight
14%5%2443345%7%43%
1910
September1st to 15thNight
17%5%3442345%6%43%
1801
16th to endNight
13%414423337%50%
1980
October1st to 15thNight
19%7%26%42335%439%
2094
16th to endNight
23%8%35%43445%6%29%
2437
November1st to 15thNight
16%10%46%424445%36%
2472
16th to endNight
17%10%46%5%35%5%35%32%
2623
December1st to 15thNight
21%12%6%7%424445%24%
2730
16th to endNight
24%14%5%7%5%34345%22%
2912

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
16%11%5%7%6%36%6%5%6%24%
1552
16th to endDay
15%12%48%7%36%45%5%26%
1693
February1st to 15thDay
17%13%5%8%8%445%5%5%20%
1731
16th to endDay
16%12%5%9%7%3434427%
1580
March1st to 15thDay
20%10%5%8%5%2445%6%26%
1800
16th to endDay
18%11%45%5%2333437%
2226
April1st to 15thDay
20%11%36%5%3433432%
2152
16th to endDay
17%8%35%5%2445%6%36%
2222
May1st to 15thDay
21%9%36%434447%30%
2409
16th to endDay
18%7%35%5%2446%7%35%
2618
June1st to 15thDay
21%6%36%5%25%46%8%28%
2520
16th to endDay
17%6%26%5%35%5%6%8%30%
2520
July1st to 15thDay
13%6%25%6%35%5%6%9%34%
2520
16th to endDay
13%5%25%6%35%6%7%8%35%
2654
August1st to 15thDay
13%6%26%6%35%6%6%8%33%
2394
16th to endDay
13%5%14435%6%6%8%39%
2292
September1st to 15thDay
17%5%15%5%25%5%5%6%40%
2158
16th to endDay
14%5%23313447%49%
1980
October1st to 15thDay
21%8%35%42334436%
1863
16th to endDay
23%11%35%5%23346%29%
1785
November1st to 15thDay
17%10%35%424347%35%
1716
16th to endDay
18%10%36%5%34445%33%
1664
December1st to 15thDay
19%13%6%7%5%24346%26%
1560
16th to endDay
22%16%6%6%5%3443322%
1664
January1st to 15thNight
17%14%49%6%34445%25%
2716
16th to endNight
14%15%5%9%6%44445%25%
2879
February1st to 15thNight
16%11%5%11%9%45%445%21%
2385
16th to endNight
15%13%49%6%35%44427%
1893
March1st to 15thNight
21%11%47%6%3433429%
2160
16th to endNight
18%9%46%434445%35%
1994
April1st to 15thNight
20%10%45%5%2434432%
1796
16th to endNight
19%9%35%324346%37%
1737
May1st to 15thNight
21%9%37%423345%35%
1554
16th to endNight
17%6%246%35%5%6%8%33%
1495
June1st to 15thNight
21%6%25%5%235%5%7%32%
1440
16th to endNight
15%4134245%5%9%41%
1440
July1st to 15thNight
13%5%35%5%26%45%9%39%
1440
16th to endNight
13%4244246%410%41%
1514
August1st to 15thNight
11%5%15%5%3445%8%43%
1548
16th to endNight
13%6%15%43445%7%43%
1910
September1st to 15thNight
17%6%2442345%5%43%
1801
16th to endNight
13%414323347%50%
1980
October1st to 15thNight
18%7%36%5%2434439%
2094
16th to endNight
23%9%35%5%2345%6%29%
2437
November1st to 15thNight
16%9%36%424436%36%
2472
16th to endNight
17%11%46%5%35%435%32%
2623
December1st to 15thNight
21%13%5%8%434446%23%
2730
16th to endNight
23%14%5%7%5%34435%21%
2912

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
58%5%10%16%7%1
1553
16th to endDay
59%413%15%5%
1693
February1st to 15thDay
64%5%9%13%5%
1734
16th to endDay
60%410%16%8%
1580
March1st to 15thDay
58%312%15%8%
1800
16th to endDay
51%39%17%14%3
2226
April1st to 15thDay
56%38%19%10%1
2152
16th to endDay
47%49%20%15%2
2222
May1st to 15thDay
54%5%8%19%11%1
2409
16th to endDay
47%6%13%20%10%1
2622
June1st to 15thDay
53%6%13%18%7%
2520
16th to endDay
49%7%14%17%11%
2520
July1st to 15thDay
44%7%12%23%10%1
2371
16th to endDay
43%7%16%20%10%
2487
August1st to 15thDay
45%7%13%22%9%
2380
16th to endDay
38%7%13%26%12%
2292
September1st to 15thDay
42%6%11%22%15%
2158
16th to endDay
34%5%9%28%19%1
1980
October1st to 15thDay
50%49%22%10%2
1863
16th to endDay
56%413%17%7%1
1785
November1st to 15thDay
48%5%13%19%11%1
1716
16th to endDay
52%412%18%10%
1664
December1st to 15thDay
60%414%14%6%
1560
16th to endDay
66%5%10%12%5%
1664
January1st to 15thNight
61%410%13%8%1
2716
16th to endNight
60%410%15%7%1
2879
February1st to 15thNight
64%5%10%12%6%
2393
16th to endNight
59%410%16%8%
1893
March1st to 15thNight
59%410%16%8%1
2160
16th to endNight
51%49%17%13%4
1995
April1st to 15thNight
54%310%18%11%
1796
16th to endNight
47%410%18%15%3
1737
May1st to 15thNight
51%49%18%14%2
1554
16th to endNight
47%8%14%18%10%1
1497
June1st to 15thNight
50%5%13%20%9%
1440
16th to endNight
37%7%16%25%11%
1440
July1st to 15thNight
39%6%13%27%12%
1360
16th to endNight
37%6%16%27%11%1
1418
August1st to 15thNight
37%6%16%27%11%
1538
16th to endNight
39%413%28%12%
1910
September1st to 15thNight
40%5%12%24%16%
1801
16th to endNight
34%410%28%20%1
1980
October1st to 15thNight
48%411%19%13%1
2094
16th to endNight
54%413%18%7%
2437
November1st to 15thNight
49%5%11%17%13%2
2472
16th to endNight
53%5%12%18%8%1
2623
December1st to 15thNight
61%5%13%14%4
2730
16th to endNight
65%49%12%6%
2912

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
22%34%28%6%6%1
90
16th to endDay
30%29%30%9%
103
February1st to 15thDay
33%36%20%6%3
175
16th to endDay
21%30%28%14%3
239
March1st to 15thDay
28%24%25%18%2
270
16th to endDay
26%26%21%15%9%1
288
April1st to 15thDay
30%21%22%17%7%1
270
16th to endDay
19%21%27%19%7%5%
270
May1st to 15thDay
32%18%19%18%7%3
288
16th to endDay
19%15%29%21%10%2
331
June1st to 15thDay
24%10%30%21%12%
315
16th to endDay
19%11%28%24%13%1
315
July1st to 15thDay
15%7%35%22%16%2
305
16th to endDay
16%5%26%30%17%2
326
August1st to 15thDay
16%8%24%27%15%6%
313
16th to endDay
15%6%18%27%18%12%
332
September1st to 15thDay
19%9%19%23%17%9%
315
16th to endDay
17%7%20%20%18%15%
314
October1st to 15thDay
24%8%21%23%17%3
315
16th to endDay
30%15%26%19%7%
302
November1st to 15thDay
26%13%24%22%12%1
280
16th to endDay
22%28%23%17%6%1
194
December1st to 15thDay
23%31%26%13%32
90
16th to endDay
27%35%31%6%
96
January1st to 15thNight
22%25%31%16%3
780
16th to endNight
23%24%31%19%1
832
February1st to 15thNight
24%25%31%16%1
753
16th to endNight
23%25%29%17%3
631
March1st to 15thNight
30%23%28%15%1
720
16th to endNight
25%24%25%19%5%
768
April1st to 15thNight
28%18%27%21%3
718
16th to endNight
24%19%30%17%8%
657
May1st to 15thNight
26%15%29%21%6%
474
16th to endNight
17%8%28%33%11%1
375
June1st to 15thNight
24%8%22%31%12%
360
16th to endNight
15%5%23%43%11%
360
July1st to 15thNight
14%325%40%15%
340
16th to endNight
13%321%42%17%1
376
August1st to 15thNight
14%322%40%16%1
467
16th to endNight
15%6%17%35%21%3
764
September1st to 15thNight
20%6%23%31%15%1
720
16th to endNight
15%5%24%27%19%6%
717
October1st to 15thNight
23%11%20%30%12%1
720
16th to endNight
28%15%26%23%5%
768
November1st to 15thNight
21%17%28%22%8%1
760
16th to endNight
22%21%26%21%6%
780
December1st to 15thNight
28%23%26%18%3
780
16th to endNight
29%24%28%15%1
832
Page generated at 2018-02-13 20:46:07. Version ac04

Copyright 2018 A. Danko


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