Woodstock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woodstock clear sky chart from 2005-11-06 to 2024-01-31.

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
25%
23152
14%
75071
6%
23101
34%
23101
15%
53019

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
15%
840
10%
2818
2%
837
24%
837
9%
2125
January11th to 20thNight
16%
760
11%
2660
3%
760
27%
760
8%
2044
January21st to endNight
19%
835
15%
2878
5%
835
31%
835
13%
1980
February1st to 10thNight
17%
720
14%
2340
5%
720
28%
720
11%
1716
February11th to 20thNight
12%
703
11%
2267
2%
700
23%
700
10%
1727
February21st to endNight
18%
592
17%
1776
5%
592
34%
592
14%
1290
March1st to 10thNight
18%
720
18%
2111
7%
720
30%
720
16%
1543
March11th to 20thNight
20%
720
16%
1980
6%
720
30%
720
16%
1451
March21st to endNight
22%
792
17%
2178
5%
792
32%
792
17%
1592
April1st to 10thNight
17%
676
14%
1824
3%
676
25%
676
14%
1370
April11th to 20thNight
19%
534
19%
1598
6%
534
30%
534
18%
1102
April21st to endNight
20%
540
15%
1620
5%
540
29%
540
15%
1175
May1st to 10thNight
24%
540
14%
1620
6%
540
32%
540
17%
1163
May11th to 20thNight
21%
532
14%
1520
7%
532
29%
532
15%
1124
May21st to endNight
25%
424
14%
1392
7%
423
35%
423
17%
956
June1st to 10thNight
28%
360
10%
1260
7%
360
35%
360
15%
910
June11th to 20thNight
35%
360
12%
1260
10%
360
42%
360
17%
840
June21st to endNight
31%
360
8%
1260
7%
360
35%
360
16%
903
July1st to 10thNight
36%
350
12%
1225
8%
350
45%
350
23%
787
July11th to 20thNight
42%
348
13%
1272
13%
348
47%
348
21%
806
July21st to endNight
43%
418
12%
1509
13%
395
48%
395
18%
995
August1st to 10thNight
43%
538
11%
1600
8%
534
46%
534
26%
1040
August11th to 20thNight
47%
532
15%
1596
10%
532
50%
532
23%
1069
August21st to endNight
45%
594
21%
1782
12%
594
51%
594
30%
1073
September1st to 10thNight
36%
625
17%
1826
8%
625
44%
625
29%
1138
September11th to 20thNight
41%
720
20%
1980
12%
720
47%
720
30%
1246
September21st to endNight
35%
720
22%
1980
11%
720
44%
720
27%
1289
October1st to 10thNight
35%
720
21%
2088
11%
720
43%
720
25%
1362
October11th to 20thNight
28%
720
17%
2160
6%
720
39%
720
19%
1491
October21st to endNight
22%
792
14%
2551
5%
792
32%
792
13%
1850
November1st to 10thNight
22%
744
16%
2416
7%
744
32%
744
16%
1683
November11th to 20thNight
24%
850
17%
2660
8%
850
35%
850
16%
1853
November21st to endNight
21%
850
13%
2660
4%
850
30%
850
12%
1956
December1st to 10thNight
15%
850
12%
2774
3%
850
24%
850
10%
2134
December11th to 20thNight
16%
850
13%
3460
4%
849
27%
849
8%
2565
December21st to endNight
13%
923
9%
5170
2%
907
24%
907
5%
3671

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
20%9%37%6%35%5%5%7%32%
74761
Night
19%9%46%6%345%5%6%33%
75371
TransparencyDay
53%5%11%20%10%1
74458
Night
52%5%11%20%10%1
75209
SeeingDay
27%14%29%20%8%2
14975
Night
26%13%30%24%7%
23164

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 10thDay
16%16%6%10%6%45%436%25%
1346
11th to 20thDay
21%13%5%8%7%34446%24%
1520
21st to endDay
13%9%410%6%46%447%33%
1705
February1st to 10thDay
14%13%48%8%5%6%5%5%6%26%
1620
11th to 20thDay
15%13%5%9%8%5%6%5%5%5%25%
1577
21st to endDay
12%11%5%8%8%45%5%5%6%31%
1480
March1st to 10thDay
19%12%49%5%45%445%28%
1845
11th to 20thDay
17%11%5%8%6%45%45%6%30%
1980
21st to endDay
16%13%6%8%6%3435%6%31%
2178
April1st to 10thDay
24%12%47%6%4445%6%24%
2132
11th to 20thDay
21%10%36%5%3445%6%33%
2312
21st to endDay
26%9%37%5%34445%31%
2340
May1st to 10thDay
25%9%36%6%34445%30%
2340
11th to 20thDay
25%8%35%5%33445%34%
2375
21st to endDay
20%7%36%5%35%5%6%8%31%
2897
June1st to 10thDay
26%8%36%6%35%5%6%6%27%
2700
11th to 20thDay
21%6%35%5%35%46%8%35%
2700
21st to endDay
26%8%46%6%35%45%7%26%
2700
July1st to 10thDay
15%7%25%6%46%6%6%8%35%
2700
11th to 20thDay
16%6%36%5%46%6%7%8%33%
2643
21st to endDay
16%7%36%6%45%6%6%9%32%
2700
August1st to 10thDay
18%6%25%5%35%6%7%8%34%
2327
11th to 20thDay
16%6%37%5%35%7%7%7%34%
2304
21st to endDay
16%6%35%6%35%5%5%7%40%
2574
September1st to 10thDay
13%6%25%6%35%5%5%7%43%
2130
11th to 20thDay
18%6%25%5%33346%46%
1980
21st to endDay
19%6%25%434348%42%
1980
October1st to 10thDay
19%9%35%5%3445%6%38%
1872
11th to 20thDay
24%8%36%5%34446%35%
1800
21st to endDay
24%11%36%6%34346%28%
1802
November1st to 10thDay
20%9%36%6%35%45%6%32%
1661
11th to 20thDay
20%9%46%5%35%5%5%7%31%
1520
21st to endDay
21%10%48%6%44447%29%
1520
December1st to 10thDay
23%11%5%9%5%46%5%4424%
1402
11th to 20thDay
22%11%5%9%7%35%445%25%
1668
21st to endDay
22%13%411%7%33435%26%
2431
January1st to 10thNight
15%14%6%10%7%35%5%5%7%23%
2818
11th to 20thNight
17%12%6%9%7%45%5%5%424%
2660
21st to endNight
12%10%5%8%7%45%6%6%6%31%
2878
February1st to 10thNight
13%14%47%7%36%5%5%6%29%
2340
11th to 20thNight
16%14%5%8%8%46%446%25%
2264
21st to endNight
14%13%47%8%35%5%45%32%
1776
March1st to 10thNight
16%14%47%7%3445%5%31%
2102
11th to 20thNight
17%10%5%7%6%35%5%5%6%32%
1979
21st to endNight
17%11%48%6%34445%34%
2178
April1st to 10thNight
24%12%37%424446%29%
1824
11th to 20thNight
22%6%35%5%44447%35%
1598
21st to endNight
28%8%35%5%3445%431%
1620
May1st to 10thNight
22%10%36%5%3435%7%31%
1620
11th to 20thNight
24%9%36%5%35%35%6%30%
1519
21st to endNight
19%7%26%6%345%6%7%35%
1391
June1st to 10thNight
24%7%36%6%45%5%47%28%
1260
11th to 20thNight
20%6%35%6%35%6%6%7%35%
1260
21st to endNight
25%8%35%5%2445%7%32%
1260
July1st to 10thNight
15%6%45%4446%8%8%38%
1260
11th to 20thNight
14%5%35%7%346%7%10%36%
1314
21st to endNight
17%5%36%6%35%5%6%8%35%
1598
August1st to 10thNight
15%5%36%5%346%6%8%40%
1612
11th to 20thNight
14%7%35%5%46%5%8%8%36%
1596
21st to endNight
13%6%245%335%48%47%
1782
September1st to 10thNight
15%5%244345%5%7%46%
1826
11th to 20thNight
17%6%24423346%48%
1980
21st to endNight
19%4245%34446%45%
1980
October1st to 10thNight
20%5%344235%5%7%40%
2088
11th to 20thNight
20%9%36%6%3446%6%35%
2160
21st to endNight
24%10%36%5%33446%32%
2551
November1st to 10thNight
21%8%36%5%25%5%5%6%34%
2416
11th to 20thNight
20%8%37%5%4445%6%34%
2660
21st to endNight
20%9%47%6%35%5%5%7%30%
2660
December1st to 10thNight
26%11%47%7%34446%25%
2774
11th to 20thNight
26%9%45%6%35%5%5%5%27%
3531
21st to endNight
21%13%48%6%3445%5%27%
5236

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
63%410%16%7%1
1347
11th to 20thDay
61%5%9%17%7%1
1520
21st to endDay
52%310%21%12%1
1705
February1st to 10thDay
59%410%19%8%1
1620
11th to 20thDay
60%49%16%9%1
1585
21st to endDay
53%5%10%20%9%3
1480
March1st to 10thDay
59%49%16%11%2
1849
11th to 20thDay
57%410%15%12%2
1980
21st to endDay
55%48%20%10%3
2178
April1st to 10thDay
59%5%9%16%10%1
2132
11th to 20thDay
52%310%21%12%2
2312
21st to endDay
57%38%17%11%4
2340
May1st to 10thDay
56%46%19%12%3
2340
11th to 20thDay
53%48%20%13%2
2379
21st to endDay
49%6%12%22%9%1
2897
June1st to 10thDay
57%5%11%17%9%1
2700
11th to 20thDay
48%5%13%20%13%2
2700
21st to endDay
58%5%12%16%8%1
2700
July1st to 10thDay
45%7%16%22%9%
2625
11th to 20thDay
45%7%14%24%9%
2562
21st to endDay
48%6%16%22%8%1
2549
August1st to 10thDay
47%6%16%25%5%
2314
11th to 20thDay
46%6%14%26%7%
2304
21st to endDay
43%6%14%26%11%
2574
September1st to 10thDay
41%5%14%27%13%
2130
11th to 20thDay
42%310%29%15%1
1980
21st to endDay
42%5%9%28%15%1
1980
October1st to 10thDay
48%411%27%10%
1872
11th to 20thDay
52%414%23%7%
1800
21st to endDay
58%412%15%11%
1802
November1st to 10thDay
53%5%11%20%11%1
1661
11th to 20thDay
53%412%19%11%1
1520
21st to endDay
57%415%18%4
1520
December1st to 10thDay
64%411%14%7%
1402
11th to 20thDay
62%48%16%9%1
1668
21st to endDay
62%410%15%8%1
2431
January1st to 10thNight
60%5%11%15%8%
2818
11th to 20thNight
62%6%9%16%7%1
2660
21st to endNight
52%5%10%22%10%1
2878
February1st to 10thNight
56%5%10%19%9%1
2340
11th to 20thNight
61%48%16%9%1
2267
21st to endNight
55%49%19%11%2
1776
March1st to 10thNight
55%47%21%11%2
2111
11th to 20thNight
53%5%10%17%14%1
1980
21st to endNight
53%48%21%12%2
2178
April1st to 10thNight
57%47%15%13%3
1824
11th to 20thNight
50%49%20%15%2
1598
21st to endNight
55%48%17%13%2
1620
May1st to 10thNight
53%48%20%12%2
1620
11th to 20thNight
56%5%8%19%11%1
1520
21st to endNight
49%6%11%20%13%1
1392
June1st to 10thNight
56%5%8%21%10%1
1260
11th to 20thNight
48%6%12%23%11%1
1260
21st to endNight
55%5%13%17%10%2
1260
July1st to 10thNight
41%8%19%24%8%
1225
11th to 20thNight
42%7%17%25%10%
1272
21st to endNight
47%6%14%21%12%
1509
August1st to 10thNight
42%6%18%27%7%
1600
11th to 20thNight
44%6%18%25%7%
1596
21st to endNight
36%417%29%13%1
1782
September1st to 10thNight
38%5%14%29%13%1
1826
11th to 20thNight
39%313%30%15%1
1980
21st to endNight
41%412%28%14%1
1980
October1st to 10thNight
43%412%26%14%
2088
11th to 20thNight
49%5%12%23%10%
2160
21st to endNight
55%5%10%20%10%
2551
November1st to 10thNight
51%5%13%22%9%1
2416
11th to 20thNight
51%413%20%10%1
2660
21st to endNight
55%6%13%17%8%1
2660
December1st to 10thNight
63%49%19%5%
2774
11th to 20thNight
59%48%18%9%
3532
21st to endNight
59%5%9%16%8%2
5236

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
32%16%33%17%3
180
11th to 20thDay
33%22%31%9%5%1
180
21st to endDay
24%19%33%15%8%1
237
February1st to 10thDay
29%16%33%18%4
340
11th to 20thDay
25%22%35%15%31
338
21st to endDay
19%23%34%20%5%
346
March1st to 10thDay
28%20%32%17%3
420
11th to 20thDay
26%18%32%15%6%2
420
21st to endDay
29%19%27%16%7%2
462
April1st to 10thDay
37%21%22%14%5%1
420
11th to 20thDay
31%18%27%17%5%1
412
21st to endDay
35%13%29%17%5%1
420
May1st to 10thDay
35%15%27%19%41
423
11th to 20thDay
32%16%27%18%6%1
521
21st to endDay
27%15%33%17%7%
680
June1st to 10thDay
33%11%28%19%7%2
630
11th to 20thDay
25%13%30%22%9%2
630
21st to endDay
30%7%30%22%10%1
630
July1st to 10thDay
20%10%32%25%12%2
620
11th to 20thDay
20%6%31%28%14%1
561
21st to endDay
16%7%32%32%10%2
488
August1st to 10thDay
16%8%32%28%14%2
446
11th to 20thDay
21%10%21%31%12%4
439
21st to endDay
21%13%24%26%13%4
495
September1st to 10thDay
16%10%35%24%12%4
450
11th to 20thDay
24%11%28%19%14%4
450
21st to endDay
22%12%28%24%9%5%
450
October1st to 10thDay
22%13%26%21%14%4
396
11th to 20thDay
32%13%27%15%10%3
360
21st to endDay
33%16%28%17%6%1
396
November1st to 10thDay
29%15%27%20%8%1
365
11th to 20thDay
28%18%30%16%8%1
370
21st to endDay
30%16%32%17%5%
370
December1st to 10thDay
31%17%30%15%42
252
11th to 20thDay
35%23%27%11%4
180
21st to endDay
32%22%30%12%31
198
January1st to 10thNight
25%18%31%22%3
840
11th to 20thNight
28%18%31%20%3
760
21st to endNight
21%17%35%22%5%
835
February1st to 10thNight
24%21%32%20%3
720
11th to 20thNight
26%18%36%16%4
703
21st to endNight
24%20%31%21%4
592
March1st to 10thNight
25%13%38%22%1
720
11th to 20thNight
28%13%33%20%6%1
720
21st to endNight
26%15%30%22%6%1
792
April1st to 10thNight
33%16%30%18%3
676
11th to 20thNight
29%15%34%17%6%
534
21st to endNight
34%11%30%18%6%
540
May1st to 10thNight
28%14%29%23%5%
540
11th to 20thNight
30%12%31%22%5%
532
21st to endNight
23%12%36%25%4
424
June1st to 10thNight
28%6%31%27%8%1
360
11th to 20thNight
22%9%28%31%9%1
360
21st to endNight
29%430%30%6%1
360
July1st to 10thNight
17%338%33%9%
350
11th to 20thNight
15%6%28%38%13%1
348
21st to endNight
20%5%26%37%13%
418
August1st to 10thNight
17%328%38%14%
538
11th to 20thNight
17%423%39%16%1
532
21st to endNight
16%6%26%36%16%1
594
September1st to 10thNight
19%6%35%28%12%
625
11th to 20thNight
20%8%25%33%13%1
720
21st to endNight
22%10%28%28%11%1
720
October1st to 10thNight
24%9%27%28%12%1
720
11th to 20thNight
25%12%29%25%9%1
720
21st to endNight
32%17%25%22%4
792
November1st to 10thNight
29%15%28%21%6%
744
11th to 20thNight
25%17%28%22%7%1
850
21st to endNight
29%16%27%23%4
850
December1st to 10thNight
34%13%30%18%41
850
11th to 20thNight
31%18%29%18%4
850
21st to endNight
30%19%29%18%31
935
Page generated at 2024-01-28 06:26:32. Version ac07

Copyright 2024 Attilla Danko


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