Big Meadow
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Meadow clear sky chart from 2005-11-06 to 2024-01-17.

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
60%
23807
32%
74630
24%
23758
69%
23758
46%
37316

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 10thNight
43%
756
25%
2646
17%
756
56%
756
31%
1450
January11th to 20thNight
44%
746
29%
2531
20%
746
60%
746
36%
1329
January21st to endNight
41%
792
31%
2574
18%
792
59%
792
33%
1429
February1st to 10thNight
43%
720
30%
2178
19%
720
58%
720
36%
1234
February11th to 20thNight
48%
700
31%
2098
22%
700
62%
700
40%
1150
February21st to endNight
41%
592
24%
1776
16%
592
52%
592
31%
1058
March1st to 10thNight
45%
720
21%
2160
15%
720
54%
720
29%
1336
March11th to 20thNight
49%
720
21%
2078
16%
720
57%
720
34%
1226
March21st to endNight
45%
792
21%
1991
10%
792
53%
792
34%
1280
April1st to 10thNight
51%
720
25%
1800
11%
720
58%
720
45%
1056
April11th to 20thNight
51%
711
27%
1779
12%
711
58%
711
44%
1041
April21st to endNight
58%
720
27%
1800
10%
720
64%
720
52%
979
May1st to 10thNight
59%
626
30%
1706
16%
626
65%
626
51%
881
May11th to 20thNight
62%
531
32%
1595
22%
531
68%
531
52%
755
May21st to endNight
58%
467
28%
1631
21%
467
67%
467
47%
727
June1st to 10thNight
69%
360
31%
1440
33%
360
77%
360
52%
565
June11th to 20thNight
73%
360
37%
1440
38%
360
83%
360
66%
482
June21st to endNight
82%
360
39%
1440
43%
360
90%
360
69%
458
July1st to 10thNight
86%
350
39%
1400
45%
350
91%
350
73%
437
July11th to 20thNight
88%
348
39%
1392
44%
348
91%
348
65%
473
July21st to endNight
82%
490
38%
1579
33%
463
86%
463
62%
627
August1st to 10thNight
82%
716
36%
1780
22%
712
84%
712
78%
812
August11th to 20thNight
88%
712
41%
1780
23%
712
91%
712
84%
774
August21st to endNight
86%
792
44%
1980
27%
792
88%
792
79%
902
September1st to 10thNight
85%
720
45%
1800
31%
720
88%
720
82%
805
September11th to 20thNight
82%
720
45%
1884
35%
720
86%
720
79%
820
September21st to endNight
75%
720
44%
1980
34%
720
85%
720
70%
880
October1st to 10thNight
72%
720
37%
2016
30%
720
80%
720
61%
948
October11th to 20thNight
68%
720
40%
2160
35%
720
77%
720
59%
971
October21st to endNight
68%
792
43%
2427
38%
792
80%
792
61%
1058
November1st to 10thNight
65%
740
33%
2405
30%
740
74%
740
46%
1160
November11th to 20thNight
60%
760
35%
2470
28%
760
71%
760
49%
1163
November21st to endNight
53%
760
32%
2470
25%
760
65%
760
41%
1263
December1st to 10thNight
48%
760
28%
2489
19%
760
60%
760
36%
1334
December11th to 20thNight
42%
760
23%
3222
19%
759
56%
759
21%
1971
December21st to endNight
38%
834
18%
4733
17%
817
53%
817
19%
2482

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
6%6%23323346%63%
74838
Night
6%5%23323346%64%
75003
TransparencyDay
25%27%22%27%16%
74549
Night
24%28%24%27%15%
74814
SeeingDay
11%12%34%31%10%2
14131
Night
9%323%37%24%3
23819

By Month

Percentage Cloud Cover SW (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 10thDay
14%9%2432335%6%49%
1519
11th to 20thDay
9%6%2431446%6%54%
1565
21st to endDay
10%10%5%442445%6%46%
1782
February1st to 10thDay
10%8%44213446%53%
1780
11th to 20thDay
7%12%5%4323435%51%
1750
21st to endDay
11%13%5%6%323346%43%
1480
March1st to 10thDay
9%15%5%5%42435%7%40%
1800
11th to 20thDay
8%11%45%5%335%5%8%43%
1880
21st to endDay
12%13%43323347%45%
2363
April1st to 10thDay
9%10%3442435%8%49%
2160
11th to 20thDay
10%10%34333346%51%
2129
21st to endDay
9%8%2323345%8%54%
2160
May1st to 10thDay
7%8%23323237%61%
2254
11th to 20thDay
5%7%2232335%7%59%
2301
21st to endDay
8%8%14323447%57%
2641
June1st to 10thDay
432342345%7%63%
2520
11th to 20thDay
2212212235%79%
2520
21st to endDay
111221222481%
2520
July1st to 10thDay
112213335%79%
2520
11th to 20thDay
2212223335%76%
2520
21st to endDay
2213313346%72%
2642
August1st to 10thDay
121222322380%
2149
11th to 20thDay
212222335%79%
2122
21st to endDay
111221223481%
2376
September1st to 10thDay
11211124480%
2160
11th to 20thDay
221231223480%
2075
21st to endDay
2312212335%76%
1980
October1st to 10thDay
45%12223335%69%
1940
11th to 20thDay
332222334473%
1800
21st to endDay
5%212223235%73%
1927
November1st to 10thDay
49%33223347%61%
1674
11th to 20thDay
6%41232345%6%64%
1710
21st to endDay
5%6%34323348%59%
1710
December1st to 10thDay
11%6%13333347%57%
1687
11th to 20thDay
15%10%445%34347%41%
1928
21st to endDay
8%9%35%5%345%6%8%43%
2794
January1st to 10thNight
12%9%1332335%6%52%
2646
11th to 20thNight
7%8%2332345%7%56%
2531
21st to endNight
10%10%24323348%52%
2574
February1st to 10thNight
10%7%23423346%55%
2178
11th to 20thNight
8%9%33323247%57%
2098
21st to endNight
10%8%47%323345%50%
1776
March1st to 10thNight
8%11%45%4245%46%46%
2160
11th to 20thNight
7%9%45%33445%9%48%
2078
21st to endNight
10%10%34423346%50%
1991
April1st to 10thNight
8%8%22324348%56%
1800
11th to 20thNight
7%7%24423246%58%
1779
21st to endNight
5%6%1331345%7%63%
1800
May1st to 10thNight
5%5%13223348%63%
1706
11th to 20thNight
5%5%22213236%69%
1594
21st to endNight
5%5%13212345%69%
1631
June1st to 10thNight
5%223212238%70%
1440
11th to 20thNight
1211112226%81%
1440
21st to endNight
11111222385%
1440
July1st to 10thNight
1211112485%
1440
11th to 20thNight
1212212246%78%
1440
21st to endNight
2112222335%76%
1672
August1st to 10thNight
11121122483%
1790
11th to 20thNight
1111123387%
1780
21st to endNight
11122212286%
1980
September1st to 10thNight
11111122288%
1800
11th to 20thNight
111121123384%
1884
21st to endNight
221121233480%
1980
October1st to 10thNight
3312213335%74%
2016
11th to 20thNight
3212323435%74%
2160
21st to endNight
4212212225%77%
2427
November1st to 10thNight
5%6%22223346%66%
2405
11th to 20thNight
6%313322349%64%
2470
21st to endNight
6%6%24324346%60%
2470
December1st to 10thNight
10%6%24413337%57%
2489
11th to 20thNight
16%9%35%42446%7%42%
3276
21st to endNight
8%7%25%5%45%5%6%8%45%
4862

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 10thDay
37%27%25%23%6%
1519
11th to 20thDay
32%38%25%21%12%
1565
21st to endDay
40%38%19%21%8%
1782
February1st to 10thDay
34%38%24%20%11%
1780
11th to 20thDay
38%38%20%24%8%
1760
21st to endDay
44%47%24%17%3
1480
March1st to 10thDay
44%49%21%17%5%
1800
11th to 20thDay
41%411%22%16%6%
1880
21st to endDay
42%415%22%13%4
2363
April1st to 10thDay
37%413%25%17%4
2160
11th to 20thDay
36%412%25%20%4
2132
21st to endDay
31%416%33%16%1
2160
May1st to 10thDay
27%311%34%21%3
2254
11th to 20thDay
26%312%33%23%3
2304
21st to endDay
29%312%33%21%2
2641
June1st to 10thDay
21%312%27%29%8%
2520
11th to 20thDay
11%19%24%38%16%
2520
21st to endDay
11%1317%43%26%
2520
July1st to 10thDay
10%2212%34%40%
2451
11th to 20thDay
13%2418%34%29%
2445
21st to endDay
16%16%20%30%27%
2495
August1st to 10thDay
11%1312%35%36%
2135
11th to 20thDay
10%2217%37%32%
2122
21st to endDay
9%1214%40%33%
2376
September1st to 10thDay
9%1313%37%37%
2160
11th to 20thDay
12%1421%36%26%
2075
21st to endDay
13%2323%40%20%
1980
October1st to 10thDay
21%2421%27%25%
1940
11th to 20thDay
17%3422%33%22%
1800
21st to endDay
17%25%22%32%22%
1927
November1st to 10thDay
26%26%23%27%15%
1674
11th to 20thDay
22%37%23%31%14%
1710
21st to endDay
26%46%19%29%16%
1710
December1st to 10thDay
30%37%19%26%15%
1687
11th to 20thDay
47%28%17%17%8%
1928
21st to endDay
41%37%22%20%8%
2794
January1st to 10thNight
34%28%26%23%8%
2646
11th to 20thNight
30%37%25%23%12%
2531
21st to endNight
33%37%21%25%11%
2574
February1st to 10thNight
33%26%24%23%11%
2178
11th to 20thNight
29%37%25%26%10%
2099
21st to endNight
37%310%24%19%6%
1776
March1st to 10thNight
39%410%22%19%6%
2160
11th to 20thNight
34%413%22%21%6%
2078
21st to endNight
37%414%28%13%4
1991
April1st to 10thNight
29%316%29%16%6%
1800
11th to 20thNight
28%414%28%21%6%
1779
21st to endNight
21%416%42%17%1
1800
May1st to 10thNight
22%313%38%22%3
1706
11th to 20thNight
20%212%41%21%4
1595
21st to endNight
21%215%34%26%2
1631
June1st to 10thNight
16%314%30%33%5%
1440
11th to 20thNight
10%110%25%39%14%
1440
21st to endNight
8%1419%42%26%
1440
July1st to 10thNight
8%1316%32%41%
1400
11th to 20thNight
10%26%19%36%28%
1392
21st to endNight
13%27%20%34%25%
1579
August1st to 10thNight
9%15%17%36%33%
1780
11th to 20thNight
6%1321%39%31%
1780
21st to endNight
8%1215%42%32%
1980
September1st to 10thNight
7%1113%36%41%
1800
11th to 20thNight
8%1425%38%23%
1884
21st to endNight
11%2323%39%22%
1980
October1st to 10thNight
16%26%23%31%23%
2016
11th to 20thNight
16%25%21%33%23%
2160
21st to endNight
14%2423%38%20%
2427
November1st to 10thNight
23%36%24%27%18%
2405
11th to 20thNight
21%38%21%32%16%
2470
21st to endNight
27%37%19%29%16%
2470
December1st to 10thNight
30%38%20%24%16%
2489
11th to 20thNight
44%39%18%18%8%
3276
21st to endNight
39%28%22%21%8%
4862

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 10thDay
28%7%34%23%6%2
180
11th to 20thDay
18%11%32%26%11%2
249
21st to endDay
19%10%34%25%11%1
374
February1st to 10thDay
18%13%32%26%8%3
412
11th to 20thDay
20%19%33%21%7%
415
21st to endDay
23%18%36%18%4
346
March1st to 10thDay
23%16%38%17%5%
420
11th to 20thDay
21%20%30%21%8%
420
21st to endDay
26%21%32%18%3
462
April1st to 10thDay
20%19%31%24%6%
420
11th to 20thDay
23%18%32%22%4
412
21st to endDay
15%16%34%24%10%2
420
May1st to 10thDay
16%20%32%23%8%1
423
11th to 20thDay
14%16%33%26%10%2
448
21st to endDay
16%14%29%27%12%2
485
June1st to 10thDay
6%14%32%31%14%3
450
11th to 20thDay
6%13%35%33%12%2
450
21st to endDay
212%35%35%13%3
450
July1st to 10thDay
2337%41%13%4
446
11th to 20thDay
2126%50%14%7%
444
21st to endDay
2230%49%10%7%
487
August1st to 10thDay
26%45%33%9%4
447
11th to 20thDay
36%35%41%10%6%
437
21st to endDay
1239%42%13%3
495
September1st to 10thDay
37%40%38%11%1
450
11th to 20thDay
311%41%36%8%1
450
21st to endDay
6%12%37%37%8%
450
October1st to 10thDay
6%19%31%35%9%
450
11th to 20thDay
5%14%37%35%9%
450
21st to endDay
7%13%34%35%10%
442
November1st to 10thDay
10%13%33%31%13%
270
11th to 20thDay
8%12%34%30%13%3
270
21st to endDay
12%13%30%32%12%1
270
December1st to 10thDay
16%11%35%28%10%
259
11th to 20thDay
16%9%38%23%14%1
180
21st to endDay
22%13%32%22%10%2
198
January1st to 10thNight
19%429%27%17%4
760
11th to 20thNight
12%7%33%32%15%2
746
21st to endNight
18%5%31%31%14%2
792
February1st to 10thNight
16%431%32%15%2
720
11th to 20thNight
13%5%30%32%17%3
704
21st to endNight
19%5%30%35%10%1
592
March1st to 10thNight
16%7%27%37%12%1
720
11th to 20thNight
15%6%25%32%19%3
720
21st to endNight
18%6%27%36%13%1
792
April1st to 10thNight
13%428%41%13%1
720
11th to 20thNight
10%6%26%38%18%1
711
21st to endNight
7%426%38%23%2
720
May1st to 10thNight
8%325%40%22%2
626
11th to 20thNight
9%319%43%22%3
531
21st to endNight
7%426%36%25%2
469
June1st to 10thNight
5%220%42%26%5%
360
11th to 20thNight
1121%44%29%4
360
21st to endNight
1213%43%39%3
360
July1st to 10thNight
19%37%50%3
350
11th to 20thNight
17%39%49%3
348
21st to endNight
211%32%49%6%
490
August1st to 10thNight
213%43%39%3
716
11th to 20thNight
18%39%47%4
712
21st to endNight
28%37%48%4
792
September1st to 10thNight
1110%40%43%5%
720
11th to 20thNight
1113%48%31%5%
720
21st to endNight
2218%39%36%4
720
October1st to 10thNight
4218%49%24%3
720
11th to 20thNight
3222%42%27%3
720
21st to endNight
5%321%35%30%6%
792
November1st to 10thNight
9%319%39%26%4
740
11th to 20thNight
8%423%43%19%3
760
21st to endNight
10%428%39%16%3
760
December1st to 10thNight
13%6%27%37%14%3
760
11th to 20thNight
19%429%32%14%2
760
21st to endNight
17%6%33%30%11%2
836
Page generated at 2024-01-13 20:56:38. Version ac07

Copyright 2024 Attilla Danko


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