Bootland Farm
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bootland Farm clear sky chart from 2005-11-05 to 2018-02-14.

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
29%
15254
13%
48842
8%
15223
36%
15223
16%
34871

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
16%
780
6%
2716
2%
776
20%
776
7%
2206
January16th to endNight
19%
832
10%
2837
4%
832
26%
832
10%
2154
February1st to 15thNight
17%
759
10%
2468
3%
757
25%
757
10%
1902
February16th to endNight
20%
631
13%
1970
5%
631
30%
631
13%
1444
March1st to 15thNight
18%
720
12%
2076
6%
720
26%
720
14%
1567
March16th to endNight
30%
768
20%
2051
9%
768
38%
768
22%
1406
April1st to 15thNight
22%
718
15%
1796
5%
718
27%
718
19%
1322
April16th to endNight
30%
639
18%
1719
8%
639
36%
639
21%
1209
May1st to 15thNight
33%
360
17%
1440
15%
360
42%
360
16%
951
May16th to endNight
34%
375
14%
1497
10%
374
47%
374
19%
937
June1st to 15thNight
34%
360
9%
1440
8%
360
43%
360
15%
950
June16th to endNight
43%
360
8%
1440
11%
360
47%
360
19%
909
July1st to 15thNight
50%
340
14%
1360
20%
340
56%
340
28%
756
July16th to endNight
56%
376
14%
1418
15%
354
62%
354
27%
808
August1st to 15thNight
51%
469
15%
1540
12%
467
56%
467
26%
955
August16th to endNight
52%
690
21%
1836
10%
690
57%
690
37%
1128
September1st to 15thNight
45%
720
15%
1800
7%
720
47%
720
28%
1247
September16th to endNight
49%
717
23%
1968
16%
717
53%
717
31%
1260
October1st to 15thNight
33%
720
16%
2160
11%
720
41%
720
20%
1487
October16th to endNight
23%
768
12%
2381
5%
768
32%
768
13%
1795
November1st to 15thNight
28%
760
16%
2557
12%
760
35%
760
15%
1817
November16th to endNight
19%
780
10%
2730
6%
780
25%
780
9%
2103
December1st to 15thNight
16%
780
7%
2730
3%
780
20%
780
7%
2209
December16th to endNight
13%
832
9%
2912
4%
832
21%
832
8%
2349

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
17%8%36%6%3445%6%32%
49246
Night
17%9%46%6%34445%32%
49012
Cloud CoverDay
31%6%25%423345%30%
49256
Night
29%7%25%42333431%
49017
TransparencyDay
51%6%11%19%9%1
48934
Night
52%5%11%19%9%
48842
SeeingDay
21%13%29%20%9%3
5847
Night
22%12%29%24%9%
15255

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
20%13%6%8%8%3444420%
1552
16th to endDay
14%15%5%8%9%35%445%22%
1737
February1st to 15thDay
12%13%6%13%7%35%44422%
1695
16th to endDay
17%12%5%7%7%45%34425%
1503
March1st to 15thDay
17%11%48%8%35%44426%
1872
16th to endDay
14%8%35%5%34345%40%
2172
April1st to 15thDay
23%10%36%42334434%
2152
16th to endDay
21%8%25%414345%36%
2250
May1st to 15thDay
20%8%36%5%23446%33%
2511
16th to endDay
17%6%35%5%35%45%6%36%
2618
June1st to 15thDay
21%7%35%5%35%35%6%31%
2520
16th to endDay
17%5%25%5%36%5%6%7%33%
2520
July1st to 15thDay
11%6%245%36%5%7%9%37%
2520
16th to endDay
11%426%5%35%5%7%10%36%
2654
August1st to 15thDay
11%6%26%6%345%6%7%37%
2409
16th to endDay
12%5%25%6%345%6%8%40%
2354
September1st to 15thDay
17%5%245%33347%41%
2160
16th to endDay
14%5%2442335%6%46%
1992
October1st to 15thDay
22%8%35%5%34446%33%
1800
16th to endDay
25%9%37%5%34345%26%
1842
November1st to 15thDay
16%9%46%5%25%5%45%34%
1629
16th to endDay
22%12%5%7%6%345%45%22%
1560
December1st to 15thDay
20%17%5%10%7%35%44416%
1560
16th to endDay
21%15%6%9%6%33335%21%
1664
January1st to 15thNight
16%15%6%10%7%46%44419%
2716
16th to endNight
13%15%5%9%7%35%43426%
2837
February1st to 15thNight
12%15%6%9%8%35%446%23%
2466
16th to endNight
16%10%48%8%35%35%5%28%
1970
March1st to 15thNight
17%13%5%7%6%3433430%
2064
16th to endNight
15%6%36%5%33346%40%
2051
April1st to 15thNight
23%8%36%5%24435%34%
1796
16th to endNight
19%9%25%5%34335%37%
1719
May1st to 15thNight
22%7%245%24335%37%
1440
16th to endNight
16%5%245%25%5%47%39%
1495
June1st to 15thNight
17%6%35%6%25%45%6%35%
1440
16th to endNight
15%5%15%5%25%5%7%7%38%
1440
July1st to 15thNight
9%5%24424448%47%
1440
16th to endNight
10%3245%345%6%9%45%
1514
August1st to 15thNight
9%425%6%335%5%9%43%
1550
16th to endNight
9%415%41435%7%50%
1836
September1st to 15thNight
15%5%25%5%2435%6%42%
1800
16th to endNight
15%4245%23345%48%
1968
October1st to 15thNight
19%7%25%434346%37%
2160
16th to endNight
22%11%36%5%34446%27%
2381
November1st to 15thNight
20%9%35%5%24445%32%
2557
16th to endNight
21%12%5%9%6%23335%24%
2730
December1st to 15thNight
20%16%6%8%7%3444419%
2730
16th to endNight
22%15%6%8%6%3434320%
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
23%13%6%6%7%3344422%
1552
16th to endDay
16%13%6%8%8%35%44424%
1737
February1st to 15thDay
18%11%5%11%7%3423425%
1695
16th to endDay
23%11%5%7%6%3333328%
1503
March1st to 15thDay
45%5%15%42323322%
1883
16th to endDay
43%41231222330%
2171
April1st to 15thDay
34%7%2431223335%
2152
16th to endDay
31%6%1331334436%
2250
May1st to 15thDay
46%5%2431223325%
2511
16th to endDay
44%31321223428%
2618
June1st to 15thDay
38%435%423335%26%
2520
16th to endDay
37%314334445%27%
2520
July1st to 15thDay
12%424425%6%6%8%40%
2520
16th to endDay
11%425%5%36%5%7%9%39%
2654
August1st to 15thDay
41%314433345%24%
2409
16th to endDay
42%313323345%27%
2354
September1st to 15thDay
22%4145%23346%41%
2160
16th to endDay
20%414423346%43%
1992
October1st to 15thDay
25%6%25%434336%34%
1800
16th to endDay
28%7%36%6%2334329%
1842
November1st to 15thDay
32%7%2442343431%
1629
16th to endDay
35%8%46%5%2334321%
1560
December1st to 15thDay
25%13%5%8%5%33335%20%
1560
16th to endDay
26%15%48%42333425%
1664
January1st to 15thNight
23%12%5%8%6%35%43322%
2716
16th to endNight
19%13%5%7%6%3443328%
2837
February1st to 15thNight
21%13%48%6%33335%26%
2459
16th to endNight
25%9%27%5%2434430%
1970
March1st to 15thNight
46%6%2432112324%
2076
16th to endNight
44%32431122331%
2051
April1st to 15thNight
31%5%1441222438%
1796
16th to endNight
25%7%24423235%39%
1719
May1st to 15thNight
42%5%1231222332%
1440
16th to endNight
37%31222243435%
1495
June1st to 15thNight
31%5%245%24435%31%
1440
16th to endNight
29%41433345%6%31%
1440
July1st to 15thNight
9%334425%45%8%49%
1440
16th to endNight
10%3144345%6%8%48%
1514
August1st to 15thNight
38%24422346%30%
1550
16th to endNight
38%23312235%35%
1836
September1st to 15thNight
20%425%423345%42%
1800
16th to endNight
22%31432223448%
1968
October1st to 15thNight
24%6%34323335%38%
2160
16th to endNight
27%9%24424335%30%
2381
November1st to 15thNight
39%7%1431332328%
2557
16th to endNight
41%9%45%42222322%
2730
December1st to 15thNight
30%13%36%5%3333323%
2730
16th to endNight
31%12%47%5%3233223%
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
65%5%9%12%6%1
1553
16th to endDay
63%6%10%12%6%
1737
February1st to 15thDay
64%410%14%4
1697
16th to endDay
60%410%13%9%1
1503
March1st to 15thDay
60%5%10%15%7%
1883
16th to endDay
45%48%19%15%5%
2172
April1st to 15thDay
54%37%18%13%2
2152
16th to endDay
48%47%18%16%3
2250
May1st to 15thDay
51%5%8%17%14%2
2511
16th to endDay
47%6%12%19%12%2
2622
June1st to 15thDay
52%6%10%20%9%
2520
16th to endDay
47%7%13%19%11%1
2520
July1st to 15thDay
38%7%14%27%12%
2371
16th to endDay
41%9%16%23%9%
2487
August1st to 15thDay
43%8%14%21%10%
2395
16th to endDay
40%7%15%26%9%
2354
September1st to 15thDay
42%5%13%26%11%
2160
16th to endDay
38%7%12%32%9%
1992
October1st to 15thDay
52%6%10%21%9%
1800
16th to endDay
60%6%12%14%5%
1842
November1st to 15thDay
49%7%15%19%7%
1629
16th to endDay
62%6%11%12%5%1
1560
December1st to 15thDay
69%6%10%10%3
1560
16th to endDay
65%5%10%11%5%
1664
January1st to 15thNight
67%6%10%10%4
2716
16th to endNight
60%5%9%16%7%
2837
February1st to 15thNight
61%5%11%16%4
2468
16th to endNight
56%412%17%9%
1970
March1st to 15thNight
58%411%18%7%
2076
16th to endNight
45%410%20%16%3
2051
April1st to 15thNight
52%48%18%14%1
1796
16th to endNight
48%47%19%17%3
1719
May1st to 15thNight
49%47%19%14%4
1440
16th to endNight
42%7%13%20%13%2
1497
June1st to 15thNight
47%7%11%22%9%1
1440
16th to endNight
42%7%15%19%14%
1440
July1st to 15thNight
33%6%13%29%15%1
1360
16th to endNight
33%7%16%27%14%
1418
August1st to 15thNight
35%9%17%24%11%
1540
16th to endNight
31%6%16%33%11%
1836
September1st to 15thNight
42%6%12%26%10%1
1800
16th to endNight
37%411%35%9%
1968
October1st to 15thNight
47%5%10%22%12%
2160
16th to endNight
57%6%14%16%5%
2381
November1st to 15thNight
52%6%12%17%9%
2557
16th to endNight
62%5%12%15%3
2730
December1st to 15thNight
67%5%12%11%3
2730
16th to endNight
67%5%9%11%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
24%25%30%16%3
90
16th to endDay
30%14%42%8%3
113
February1st to 15thDay
29%23%37%8%1
130
16th to endDay
32%22%26%14%4
162
March1st to 15thDay
25%18%33%18%4
270
16th to endDay
22%18%29%18%8%1
288
April1st to 15thDay
27%23%26%14%6%
270
16th to endDay
24%17%27%17%8%4
270
May1st to 15thDay
30%11%28%17%8%3
288
16th to endDay
24%14%30%20%8%2
331
June1st to 15thDay
27%11%29%21%7%1
315
16th to endDay
15%11%35%24%11%1
315
July1st to 15thDay
13%6%32%28%13%5%
305
16th to endDay
11%6%32%30%15%4
326
August1st to 15thDay
13%5%25%35%11%8%
313
16th to endDay
14%5%26%27%15%9%
332
September1st to 15thDay
17%7%25%18%17%13%
315
16th to endDay
14%9%24%21%20%9%
314
October1st to 15thDay
22%11%30%20%11%2
315
16th to endDay
27%21%28%16%5%
316
November1st to 15thDay
23%13%29%23%7%2
193
16th to endDay
30%23%35%6%4
90
December1st to 15thDay
23%24%35%14%2
90
16th to endDay
36%27%28%6%2
96
January1st to 15thNight
24%18%34%17%4
780
16th to endNight
22%16%34%22%3
832
February1st to 15thNight
20%16%37%21%3
760
16th to endNight
22%17%33%20%5%
631
March1st to 15thNight
25%16%32%22%2
720
16th to endNight
19%16%28%24%10%
768
April1st to 15thNight
27%16%29%21%5%
718
16th to endNight
25%14%27%24%8%
639
May1st to 15thNight
26%7%27%27%9%1
360
16th to endNight
18%6%37%26%11%
375
June1st to 15thNight
18%8%31%32%8%
360
16th to endNight
17%6%25%36%12%
360
July1st to 15thNight
9%428%39%17%1
340
16th to endNight
9%224%44%15%2
376
August1st to 15thNight
12%423%38%19%2
469
16th to endNight
11%426%35%20%2
690
September1st to 15thNight
18%5%25%28%19%2
720
16th to endNight
17%7%21%26%23%2
717
October1st to 15thNight
24%10%27%24%12%1
720
16th to endNight
28%15%27%21%6%
768
November1st to 15thNight
25%10%30%21%10%
760
16th to endNight
30%19%24%18%6%
780
December1st to 15thNight
29%17%32%17%3
780
16th to endNight
31%14%33%16%3
832
Page generated at 2018-02-15 10:58:47. Version ac04

Copyright 2018 A. Danko


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