Cold Spring
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cold Spring clear sky chart from 2005-11-06 to 2024-02-10.

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
36%
24996
16%
80149
9%
24904
43%
24904
22%
53361

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
27%
940
11%
4686
6%
926
35%
926
11%
3361
January11th to 20thNight
25%
945
9%
4283
5%
930
30%
930
10%
3214
January21st to endNight
23%
1032
10%
4480
4%
1023
29%
1023
10%
3295
February1st to 10thNight
28%
948
16%
2464
4%
948
36%
948
24%
1696
February11th to 20thNight
28%
879
19%
2274
5%
875
36%
875
26%
1542
February21st to endNight
31%
740
17%
1924
5%
740
40%
740
22%
1374
March1st to 10thNight
32%
547
15%
1987
9%
547
40%
547
19%
1304
March11th to 20thNight
28%
540
19%
1980
10%
540
41%
540
21%
1240
March21st to endNight
31%
594
15%
2178
13%
594
39%
594
17%
1480
April1st to 10thNight
27%
540
17%
1819
10%
540
39%
540
21%
1194
April11th to 20thNight
32%
533
20%
1688
16%
533
43%
533
20%
1150
April21st to endNight
34%
540
17%
1620
12%
540
43%
540
21%
1123
May1st to 10thNight
34%
540
15%
1566
8%
540
40%
540
26%
1043
May11th to 20thNight
41%
531
18%
1417
8%
531
46%
531
27%
950
May21st to endNight
45%
584
15%
1552
6%
582
49%
582
33%
990
June1st to 10thNight
50%
540
15%
1403
6%
540
53%
540
37%
874
June11th to 20thNight
48%
540
17%
1260
6%
540
52%
540
41%
811
June21st to endNight
53%
540
17%
1260
7%
540
56%
540
43%
791
July1st to 10thNight
65%
525
19%
1225
8%
525
67%
525
55%
699
July11th to 20thNight
60%
522
23%
1317
9%
522
63%
522
50%
737
July21st to endNight
66%
591
22%
1560
13%
558
68%
558
50%
824
August1st to 10thNight
63%
537
21%
1601
17%
534
67%
534
39%
910
August11th to 20thNight
61%
534
22%
1600
20%
534
67%
534
37%
911
August21st to endNight
58%
594
25%
1836
24%
594
65%
594
41%
967
September1st to 10thNight
55%
540
22%
1800
21%
540
63%
540
38%
934
September11th to 20thNight
49%
540
25%
1890
21%
540
58%
540
34%
1015
September21st to endNight
40%
566
25%
2006
15%
566
54%
566
30%
1107
October1st to 10thNight
39%
720
22%
2160
13%
720
46%
720
29%
1317
October11th to 20thNight
31%
720
22%
2160
10%
720
40%
720
25%
1372
October21st to endNight
29%
792
19%
2376
9%
792
38%
792
21%
1601
November1st to 10thNight
34%
925
20%
2568
10%
925
43%
925
26%
1674
November11th to 20thNight
27%
950
17%
2660
7%
950
36%
950
19%
1912
November21st to endNight
27%
950
17%
2660
7%
950
35%
950
23%
1777
December1st to 10thNight
26%
950
12%
2660
5%
950
33%
950
18%
1925
December11th to 20thNight
21%
949
12%
3207
3%
949
30%
949
13%
2337
December21st to endNight
19%
1038
7%
5022
4%
1026
27%
1026
7%
3910

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
12%9%47%6%35%5%5%7%37%
78376
Night
11%9%47%6%35%45%7%39%
80627
TransparencyDay
46%5%14%24%10%1
78071
Night
45%5%13%24%11%1
80452
SeeingDay
16%8%31%28%14%3
14943
Night
16%8%32%32%11%1
25032

By Month

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 10thDay
11%14%5%12%10%46%5%5%6%22%
2221
11th to 20thDay
5%9%413%11%6%8%7%8%5%23%
2626
21st to endDay
6%16%10%11%7%46%5%6%6%24%
3135
February1st to 10thDay
9%11%6%7%7%5%5%45%6%35%
1701
11th to 20thDay
7%11%5%10%8%46%5%7%6%32%
1574
21st to endDay
10%11%5%10%9%46%5%5%6%31%
1340
March1st to 10thDay
12%12%5%8%7%35%5%5%7%32%
1980
11th to 20thDay
14%11%47%435%447%37%
1980
21st to endDay
18%11%5%8%4445%5%6%30%
2178
April1st to 10thDay
17%10%47%5%335%5%7%35%
2140
11th to 20thDay
18%14%5%6%6%34446%31%
2219
21st to endDay
23%8%5%5%6%25%45%6%31%
2340
May1st to 10thDay
18%8%47%6%35%5%5%6%34%
2391
11th to 20thDay
16%8%37%5%35%5%5%7%38%
2479
21st to endDay
15%7%35%5%35%5%5%9%38%
2725
June1st to 10thDay
12%5%25%5%35%5%6%8%45%
2552
11th to 20thDay
13%6%37%5%35%5%5%9%39%
2700
21st to endDay
9%5%25%6%36%5%7%11%42%
2700
July1st to 10thDay
6%3245%35%6%7%10%50%
2700
11th to 20thDay
8%4245%25%5%5%8%52%
2597
21st to endDay
5%424436%6%7%10%50%
2663
August1st to 10thDay
8%5%36%6%36%6%6%9%42%
2328
11th to 20thDay
13%5%25%5%345%6%8%45%
2301
21st to endDay
10%425%42445%8%53%
2520
September1st to 10thDay
9%5%25%5%3445%9%49%
2160
11th to 20thDay
11%5%25%5%346%6%7%46%
2066
21st to endDay
16%5%35%42345%8%44%
1936
October1st to 10thDay
18%8%25%43346%8%39%
1800
11th to 20thDay
15%10%36%5%34447%39%
1800
21st to endDay
17%10%46%5%34347%37%
1979
November1st to 10thDay
14%10%47%5%35%45%6%37%
1510
11th to 20thDay
9%12%6%12%8%3445%7%30%
1520
21st to endDay
13%10%5%7%5%345%5%8%35%
1520
December1st to 10thDay
10%12%5%9%10%46%6%5%7%27%
1520
11th to 20thDay
10%14%7%9%7%35%45%7%28%
1918
21st to endDay
22%14%5%14%6%34345%21%
2557
January1st to 10thNight
10%11%7%15%8%3445%5%28%
4727
11th to 20thNight
6%12%411%10%6%9%8%7%6%21%
4340
21st to endNight
8%19%9%10%6%3445%6%26%
4532
February1st to 10thNight
6%11%5%9%7%35%5%6%7%36%
2464
11th to 20thNight
6%8%5%8%5%36%5%5%9%39%
2273
21st to endNight
12%10%47%6%45%5%6%6%35%
1924
March1st to 10thNight
12%10%37%5%35%5%5%8%36%
1987
11th to 20thNight
12%10%46%5%3435%5%42%
1980
21st to endNight
17%10%47%5%35%45%7%33%
2178
April1st to 10thNight
14%10%36%5%36%447%39%
1819
11th to 20thNight
18%11%47%43445%5%36%
1688
21st to endNight
19%9%37%434446%37%
1620
May1st to 10thNight
15%8%45%43445%7%41%
1566
11th to 20thNight
15%5%25%5%35%5%5%6%42%
1416
21st to endNight
13%5%25%5%3447%8%45%
1551
June1st to 10thNight
10%423435%6%6%9%47%
1403
11th to 20thNight
8%5%25%5%35%46%9%48%
1260
21st to endNight
7%415%5%345%5%8%53%
1260
July1st to 10thNight
33133245%7%8%60%
1260
11th to 20thNight
6%41332336%8%60%
1360
21st to endNight
42144245%6%8%61%
1652
August1st to 10thNight
7%4344245%6%9%50%
1611
11th to 20thNight
11%42442445%6%54%
1600
21st to endNight
8%423324447%59%
1836
September1st to 10thNight
8%32443446%7%56%
1800
11th to 20thNight
10%5%24434447%54%
1890
21st to endNight
13%5%2442345%6%51%
2006
October1st to 10thNight
15%6%25%4235%47%48%
2160
11th to 20thNight
15%8%345%3445%7%43%
2160
21st to endNight
17%9%47%5%24347%38%
2376
November1st to 10thNight
12%8%36%5%35%46%7%41%
2568
11th to 20thNight
12%10%5%9%6%35%445%35%
2660
21st to endNight
12%8%37%6%3445%7%40%
2660
December1st to 10thNight
10%9%6%10%8%5%5%45%7%31%
2660
11th to 20thNight
11%12%5%10%9%45%6%5%6%28%
3279
21st to endNight
21%14%6%10%7%34445%21%
5101

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
62%5%12%17%4
2222
11th to 20thDay
59%414%18%5%
2626
21st to endDay
61%5%14%16%5%
3135
February1st to 10thDay
50%412%23%9%1
1701
11th to 20thDay
51%6%13%22%7%1
1583
21st to endDay
54%5%9%20%11%1
1340
March1st to 10thDay
53%5%13%20%8%1
1980
11th to 20thDay
48%5%15%23%9%1
1980
21st to endDay
55%5%11%21%7%
2178
April1st to 10thDay
49%412%21%12%1
2140
11th to 20thDay
55%410%19%11%2
2219
21st to endDay
53%5%12%20%10%1
2340
May1st to 10thDay
50%5%13%20%10%1
2391
11th to 20thDay
46%5%12%25%11%1
2483
21st to endDay
43%6%13%24%11%2
2725
June1st to 10thDay
37%5%16%30%11%1
2552
11th to 20thDay
42%7%14%22%14%1
2700
21st to endDay
35%6%19%28%10%2
2700
July1st to 10thDay
26%7%18%32%17%1
2626
11th to 20thDay
29%7%16%27%18%3
2517
21st to endDay
27%8%16%31%16%2
2515
August1st to 10thDay
37%6%16%27%10%3
2314
11th to 20thDay
36%6%17%30%10%1
2301
21st to endDay
29%5%14%35%15%2
2520
September1st to 10thDay
31%5%14%36%13%
2160
11th to 20thDay
36%5%19%30%9%1
2066
21st to endDay
40%5%12%33%9%1
1936
October1st to 10thDay
42%5%14%26%12%
1800
11th to 20thDay
45%5%11%25%12%2
1800
21st to endDay
49%313%25%9%
1979
November1st to 10thDay
47%5%12%20%13%3
1510
11th to 20thDay
55%413%18%9%1
1520
21st to endDay
48%416%23%7%2
1520
December1st to 10thDay
57%5%14%18%6%
1520
11th to 20thDay
57%416%19%5%
1915
21st to endDay
67%49%14%6%
2557
January1st to 10thNight
58%412%19%6%1
4727
11th to 20thNight
61%5%12%16%5%
4340
21st to endNight
60%410%20%6%1
4532
February1st to 10thNight
47%414%23%11%2
2464
11th to 20thNight
42%5%15%24%12%2
2274
21st to endNight
49%5%11%21%13%2
1924
March1st to 10thNight
46%6%15%25%8%
1987
11th to 20thNight
45%313%24%14%1
1980
21st to endNight
51%5%11%25%7%2
2178
April1st to 10thNight
46%5%10%26%13%1
1819
11th to 20thNight
49%47%23%15%2
1688
21st to endNight
49%5%9%22%13%2
1620
May1st to 10thNight
42%6%13%24%14%1
1566
11th to 20thNight
41%7%12%24%15%3
1417
21st to endNight
36%5%16%23%16%3
1552
June1st to 10thNight
32%7%17%29%14%2
1403
11th to 20thNight
31%6%17%27%15%3
1260
21st to endNight
29%5%16%29%17%3
1260
July1st to 10thNight
20%5%19%34%20%1
1225
11th to 20thNight
22%5%14%37%17%5%
1317
21st to endNight
21%5%16%37%16%5%
1560
August1st to 10thNight
30%5%17%32%13%4
1601
11th to 20thNight
31%5%17%31%15%1
1600
21st to endNight
25%6%14%32%20%4
1836
September1st to 10thNight
27%5%17%34%17%1
1800
11th to 20thNight
31%417%31%17%
1890
21st to endNight
33%413%34%16%1
2006
October1st to 10thNight
37%5%11%31%15%2
2160
11th to 20thNight
41%413%26%14%2
2160
21st to endNight
47%413%24%11%1
2376
November1st to 10thNight
41%5%14%25%13%2
2568
11th to 20thNight
52%413%18%12%1
2660
21st to endNight
44%418%24%7%2
2660
December1st to 10thNight
53%415%20%7%
2660
11th to 20thNight
56%5%13%18%6%1
3281
21st to endNight
66%49%16%5%
5101

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
16%8%31%31%13%2
270
11th to 20thDay
17%9%39%31%5%
270
21st to endDay
13%9%40%22%14%2
297
February1st to 10thDay
15%15%43%22%3
267
11th to 20thDay
14%21%36%22%7%
240
21st to endDay
19%11%38%28%31
198
March1st to 10thDay
20%12%38%23%6%1
240
11th to 20thDay
22%8%36%24%9%2
240
21st to endDay
23%11%28%24%11%3
264
April1st to 10thDay
27%14%29%24%6%
400
11th to 20thDay
28%12%26%24%10%1
497
21st to endDay
24%8%36%20%10%2
600
May1st to 10thDay
23%9%34%25%8%2
603
11th to 20thDay
20%9%30%25%12%4
625
21st to endDay
18%6%28%32%14%3
679
June1st to 10thDay
11%7%25%31%22%4
630
11th to 20thDay
16%6%33%31%13%1
630
21st to endDay
12%6%32%28%17%5%
630
July1st to 10thDay
7%422%34%23%9%
621
11th to 20thDay
10%6%29%29%18%8%
618
21st to endDay
7%425%36%22%6%
684
August1st to 10thDay
10%321%34%27%5%
626
11th to 20thDay
12%5%21%34%23%6%
615
21st to endDay
10%6%23%34%22%5%
639
September1st to 10thDay
13%6%29%33%16%4
450
11th to 20thDay
11%331%31%19%5%
356
21st to endDay
24%10%28%20%13%4
270
October1st to 10thDay
19%11%30%21%13%6%
270
11th to 20thDay
16%16%37%21%9%2
270
21st to endDay
24%14%37%18%6%1
297
November1st to 10thDay
22%11%30%27%7%2
270
11th to 20thDay
17%17%40%22%4
270
21st to endDay
20%14%37%23%5%
270
December1st to 10thDay
14%10%42%24%10%
270
11th to 20thDay
19%13%38%26%3
270
21st to endDay
31%11%34%21%3
297
January1st to 10thNight
11%11%36%31%8%2
950
11th to 20thNight
16%10%37%29%7%1
950
21st to endNight
17%12%35%27%9%
1045
February1st to 10thNight
11%11%39%30%9%1
948
11th to 20thNight
11%12%40%28%7%1
879
21st to endNight
16%11%32%31%8%2
740
March1st to 10thNight
16%10%35%28%10%1
547
11th to 20thNight
16%9%41%27%6%1
540
21st to endNight
23%8%30%26%10%2
594
April1st to 10thNight
19%8%40%26%7%
540
11th to 20thNight
23%11%29%28%9%1
533
21st to endNight
23%7%30%31%8%2
540
May1st to 10thNight
19%8%33%29%10%1
540
11th to 20thNight
17%7%30%33%11%1
531
21st to endNight
15%6%27%36%15%1
584
June1st to 10thNight
14%427%38%18%1
540
11th to 20thNight
11%331%44%10%
540
21st to endNight
9%428%41%18%1
540
July1st to 10thNight
5%222%43%27%1
525
11th to 20thNight
8%225%47%16%2
522
21st to endNight
6%123%46%22%2
591
August1st to 10thNight
9%117%50%21%2
537
11th to 20thNight
12%118%40%26%3
534
21st to endNight
9%324%39%23%2
594
September1st to 10thNight
11%425%41%18%2
540
11th to 20thNight
11%6%29%32%21%1
540
21st to endNight
15%8%33%30%12%2
566
October1st to 10thNight
16%9%31%31%12%1
720
11th to 20thNight
21%9%34%29%6%1
720
21st to endNight
23%11%30%28%7%
792
November1st to 10thNight
16%11%32%32%9%1
925
11th to 20thNight
18%12%34%27%8%1
950
21st to endNight
16%13%36%26%8%
950
December1st to 10thNight
15%11%35%30%8%1
950
11th to 20thNight
21%8%36%29%6%1
950
21st to endNight
25%10%33%26%6%1
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