Cold Spring
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cold Spring clear sky chart from 2005-11-05 to 2017-12-01.

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
38%
16470
17%
47609
9%
16423
44%
16423
26%
31360

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
29%
900
13%
2619
7%
895
35%
895
19%
1857
January16th to endNight
24%
960
13%
2517
4%
960
31%
960
19%
1870
February1st to 15thNight
32%
879
14%
2288
4%
875
39%
875
24%
1570
February16th to endNight
32%
789
16%
2051
5%
789
39%
789
23%
1446
March1st to 15thNight
35%
545
15%
1985
10%
545
42%
545
20%
1295
March16th to endNight
32%
576
15%
2112
12%
576
40%
576
18%
1428
April1st to 15thNight
31%
539
18%
1809
13%
539
42%
539
23%
1170
April16th to endNight
33%
540
18%
1620
12%
540
42%
540
19%
1154
May1st to 15thNight
33%
540
14%
1524
6%
540
39%
540
23%
1065
May16th to endNight
44%
563
15%
1498
6%
561
49%
561
31%
966
June1st to 15thNight
46%
540
13%
1355
4%
540
50%
540
36%
868
June16th to endNight
54%
540
16%
1260
6%
540
58%
540
45%
782
July1st to 15thNight
60%
510
17%
1198
7%
510
62%
510
50%
703
July16th to endNight
65%
564
21%
1465
12%
531
67%
531
48%
796
August1st to 15thNight
64%
539
22%
1610
18%
536
67%
536
39%
904
August16th to endNight
60%
573
23%
1755
20%
573
67%
573
39%
950
September1st to 15thNight
57%
540
23%
1800
21%
540
64%
540
38%
951
September16th to endNight
41%
555
23%
1998
16%
555
54%
555
31%
1105
October1st to 15thNight
39%
720
23%
2160
13%
720
46%
720
31%
1299
October16th to endNight
33%
768
18%
2304
10%
768
40%
768
22%
1527
November1st to 15thNight
35%
950
19%
2646
9%
950
42%
950
26%
1734
November16th to endNight
30%
975
17%
2730
9%
975
37%
975
23%
1849
December1st to 15thNight
26%
905
11%
2533
4%
905
32%
905
17%
1879
December16th to endNight
22%
960
12%
2772
3%
960
30%
960
12%
2192

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
13%8%36%5%3445%7%37%
48816
Night
12%8%35%5%2445%6%41%
47772
Cloud CoverDay
13%8%36%5%3445%7%37%
48827
Night
12%8%35%5%2445%6%41%
47776
Cloud CoverDay
13%8%36%5%3445%7%37%
48825
Night
11%8%36%5%2445%7%40%
47776
TransparencyDay
45%5%14%23%9%1
48497
Night
42%414%24%11%1
47609
SeeingDay
16%7%28%28%15%3
6374
Night
15%8%30%32%12%1
16471

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
8%12%5%9%7%46%6%5%7%26%
1315
16th to endDay
9%14%5%9%7%46%6%5%6%24%
1704
February1st to 15thDay
9%11%5%9%6%35%445%33%
1575
16th to endDay
10%10%5%10%7%36%46%6%28%
1428
March1st to 15thDay
14%10%5%7%6%24446%33%
1969
16th to endDay
17%10%47%5%25%346%31%
2112
April1st to 15thDay
16%9%35%5%23347%36%
2138
16th to endDay
23%11%45%424445%28%
2338
May1st to 15thDay
20%8%37%6%34445%32%
2426
16th to endDay
15%7%25%5%25%6%5%8%35%
2617
June1st to 15thDay
15%6%35%6%25%46%7%35%
2601
16th to endDay
9%425%5%35%46%10%42%
2700
July1st to 15thDay
6%324425%5%6%9%49%
2691
16th to endDay
6%4134345%7%9%49%
2602
August1st to 15thDay
9%5%25%6%36%6%5%7%41%
2340
16th to endDay
13%424323448%48%
2446
September1st to 15thDay
9%41433345%8%49%
2157
16th to endDay
15%6%244235%47%43%
1950
October1st to 15thDay
17%7%14422447%42%
1800
16th to endDay
19%8%35%423336%37%
1918
November1st to 15thDay
13%11%36%43335%6%38%
1542
16th to endDay
13%8%47%6%35%45%7%32%
1560
December1st to 15thDay
13%13%5%7%9%35%446%26%
1441
16th to endDay
17%15%8%10%5%24336%21%
1446
January1st to 15thNight
8%9%6%8%7%36%5%6%6%31%
2619
16th to endNight
11%13%6%7%5%35%46%7%28%
2517
February1st to 15thNight
7%11%47%5%35%45%7%37%
2285
16th to endNight
8%8%5%7%6%36%6%47%36%
2051
March1st to 15thNight
12%10%45%5%25%446%38%
1973
16th to endNight
15%9%46%5%2445%6%34%
2112
April1st to 15thNight
15%10%35%333345%41%
1809
16th to endNight
21%9%36%42333435%
1620
May1st to 15thNight
19%8%24334446%38%
1524
16th to endNight
13%42442445%8%43%
1496
June1st to 15thNight
12%323325%46%9%45%
1355
16th to endNight
7%22342436%7%54%
1260
July1st to 15thNight
42143225%6%9%56%
1268
16th to endNight
421232435%9%59%
1565
August1st to 15thNight
8%3244235%5%7%53%
1620
16th to endNight
9%212324346%57%
1755
September1st to 15thNight
8%413323446%57%
1800
16th to endNight
11%424413347%51%
1998
October1st to 15thNight
13%5%23423436%49%
2160
16th to endNight
18%8%34423345%40%
2304
November1st to 15thNight
12%8%35%43435%6%41%
2646
16th to endNight
12%8%37%43445%6%39%
2730
December1st to 15thNight
12%10%5%9%7%35%336%30%
2533
16th to endNight
16%14%5%8%8%35%446%22%
2772

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 15thDay
8%12%5%8%8%46%5%5%7%26%
1315
16th to endDay
9%13%5%9%6%36%6%5%6%24%
1704
February1st to 15thDay
8%11%6%8%6%45%45%5%33%
1575
16th to endDay
10%10%410%7%36%45%6%28%
1428
March1st to 15thDay
13%11%5%7%6%24446%33%
1980
16th to endDay
17%11%47%5%25%346%30%
2112
April1st to 15thDay
16%9%36%5%23347%36%
2138
16th to endDay
23%11%45%5%24445%28%
2338
May1st to 15thDay
20%8%47%6%34445%32%
2426
16th to endDay
15%6%36%425%6%5%8%35%
2617
June1st to 15thDay
14%6%36%6%25%46%7%35%
2601
16th to endDay
9%4245%25%5%6%10%42%
2700
July1st to 15thDay
6%324425%5%6%9%49%
2691
16th to endDay
6%413435%5%6%9%49%
2602
August1st to 15thDay
8%5%246%46%6%6%7%41%
2340
16th to endDay
13%324323448%47%
2446
September1st to 15thDay
9%41433346%8%49%
2157
16th to endDay
15%5%244245%48%42%
1950
October1st to 15thDay
17%7%25%42335%7%41%
1800
16th to endDay
19%9%36%423236%36%
1918
November1st to 15thDay
13%10%37%42345%5%38%
1542
16th to endDay
14%8%47%6%3446%7%32%
1560
December1st to 15thDay
13%14%47%9%35%35%6%25%
1441
16th to endDay
17%15%8%10%5%24345%21%
1446
January1st to 15thNight
8%9%6%8%7%36%5%6%6%31%
2619
16th to endNight
10%13%5%8%5%35%46%7%28%
2517
February1st to 15thNight
7%11%47%5%35%45%8%37%
2278
16th to endNight
8%8%5%7%6%35%6%5%7%36%
2051
March1st to 15thNight
11%10%45%435%446%38%
1985
16th to endNight
15%9%47%5%2445%6%34%
2112
April1st to 15thNight
15%10%25%323346%41%
1809
16th to endNight
21%9%46%324435%35%
1620
May1st to 15thNight
18%7%35%333446%37%
1523
16th to endNight
13%5%24425%46%8%43%
1496
June1st to 15thNight
11%433335%46%9%45%
1355
16th to endNight
7%31342445%8%54%
1260
July1st to 15thNight
421432346%9%57%
1268
16th to endNight
421232345%8%59%
1565
August1st to 15thNight
8%32442345%7%52%
1620
16th to endNight
9%312324446%57%
1755
September1st to 15thNight
7%414323446%57%
1800
16th to endNight
11%424422347%50%
1998
October1st to 15thNight
13%6%23423336%49%
2160
16th to endNight
18%8%34423345%40%
2304
November1st to 15thNight
12%8%35%43435%6%42%
2646
16th to endNight
12%8%37%434446%39%
2730
December1st to 15thNight
12%10%5%8%7%36%346%30%
2533
16th to endNight
16%14%6%8%7%35%445%22%
2772

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
8%12%5%9%8%45%6%47%27%
1315
16th to endDay
9%13%5%10%6%36%5%6%6%24%
1704
February1st to 15thDay
8%11%6%8%6%35%45%5%33%
1575
16th to endDay
9%10%410%8%36%5%6%5%29%
1428
March1st to 15thDay
13%10%5%8%5%24446%33%
1980
16th to endDay
17%11%47%434446%31%
2110
April1st to 15thDay
16%9%36%423446%36%
2138
16th to endDay
23%11%5%5%5%25%345%28%
2338
May1st to 15thDay
19%8%47%6%34435%32%
2426
16th to endDay
14%6%26%5%35%5%6%8%35%
2617
June1st to 15thDay
14%6%36%5%245%5%7%35%
2601
16th to endDay
9%425%5%25%5%6%10%42%
2700
July1st to 15thDay
6%3135%25%5%6%9%48%
2691
16th to endDay
5%413425%5%6%10%48%
2602
August1st to 15thDay
8%5%25%6%37%5%5%7%41%
2340
16th to endDay
13%41442345%8%47%
2446
September1st to 15thDay
8%5%1443446%8%48%
2157
16th to endDay
14%6%24423447%42%
1950
October1st to 15thDay
17%8%15%422347%41%
1800
16th to endDay
18%9%35%5%24246%36%
1918
November1st to 15thDay
13%10%47%42445%5%38%
1542
16th to endDay
14%8%37%6%3445%8%31%
1560
December1st to 15thDay
13%13%5%7%9%35%446%25%
1441
16th to endDay
17%16%8%9%5%34336%21%
1446
January1st to 15thNight
8%9%5%8%7%36%5%6%6%31%
2619
16th to endNight
11%13%5%8%5%3446%7%27%
2517
February1st to 15thNight
7%11%47%5%2445%7%37%
2278
16th to endNight
8%9%48%6%35%5%6%7%35%
2051
March1st to 15thNight
11%10%45%425%446%38%
1985
16th to endNight
15%9%38%5%25%45%6%34%
2112
April1st to 15thNight
14%9%35%424345%41%
1809
16th to endNight
21%10%37%32333435%
1620
May1st to 15thNight
18%8%35%433446%37%
1523
16th to endNight
12%5%2442447%8%43%
1496
June1st to 15thNight
11%4234245%6%8%46%
1355
16th to endNight
7%31432445%8%54%
1260
July1st to 15thNight
43332447%8%57%
1268
16th to endNight
421331345%9%59%
1565
August1st to 15thNight
7%32442445%8%52%
1620
16th to endNight
9%313314447%56%
1755
September1st to 15thNight
7%414324346%57%
1800
16th to endNight
11%424423447%50%
1998
October1st to 15thNight
13%5%24423436%49%
2160
16th to endNight
18%8%35%423336%40%
2304
November1st to 15thNight
12%7%35%42435%6%41%
2646
16th to endNight
12%8%36%6%24446%39%
2730
December1st to 15thNight
12%9%5%9%7%45%346%30%
2533
16th to endNight
16%14%6%8%8%44446%22%
2772

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
54%5%12%18%8%
1316
16th to endDay
57%5%15%17%4
1704
February1st to 15thDay
51%414%20%6%1
1576
16th to endDay
54%5%11%22%5%
1428
March1st to 15thDay
51%5%13%20%7%
1980
16th to endDay
53%5%13%23%3
2112
April1st to 15thDay
47%412%21%11%1
2138
16th to endDay
57%312%16%9%1
2338
May1st to 15thDay
53%412%20%7%
2426
16th to endDay
45%5%13%23%10%1
2621
June1st to 15thDay
46%5%15%24%7%
2601
16th to endDay
35%5%17%28%11%1
2700
July1st to 15thDay
28%6%16%29%16%1
2532
16th to endDay
28%7%18%27%15%1
2439
August1st to 15thDay
38%6%14%27%9%2
2326
16th to endDay
34%5%15%29%13%1
2446
September1st to 15thDay
31%5%17%34%11%
2157
16th to endDay
40%5%13%31%8%
1950
October1st to 15thDay
41%414%26%12%1
1800
16th to endDay
49%313%23%9%
1918
November1st to 15thDay
46%412%22%13%1
1542
16th to endDay
50%418%17%8%1
1560
December1st to 15thDay
59%413%16%5%
1441
16th to endDay
65%39%15%5%
1446
January1st to 15thNight
50%5%12%21%9%
2619
16th to endNight
53%415%19%6%
2517
February1st to 15thNight
45%417%22%9%
2288
16th to endNight
46%5%13%22%11%
2051
March1st to 15thNight
46%5%15%23%9%
1985
16th to endNight
49%5%13%25%5%
2112
April1st to 15thNight
45%310%26%12%1
1809
16th to endNight
52%48%18%13%2
1620
May1st to 15thNight
46%6%11%22%12%1
1524
16th to endNight
37%5%14%24%15%2
1498
June1st to 15thNight
34%5%17%28%12%1
1355
16th to endNight
27%5%15%30%16%4
1260
July1st to 15thNight
23%5%17%33%17%2
1198
16th to endNight
21%6%15%34%17%4
1465
August1st to 15thNight
29%415%31%14%3
1610
16th to endNight
27%5%15%30%18%3
1755
September1st to 15thNight
27%5%15%33%17%
1800
16th to endNight
33%414%32%14%
1998
October1st to 15thNight
35%411%30%16%2
2160
16th to endNight
45%414%23%11%
2304
November1st to 15thNight
42%314%24%13%1
2646
16th to endNight
45%418%20%9%1
2730
December1st to 15thNight
54%414%19%5%
2533
16th to endNight
63%411%14%5%
2772

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
20%10%34%26%8%
90
16th to endDay
21%12%32%22%10%
96
February1st to 15thDay
14%23%41%16%4
90
16th to endDay
17%13%34%27%6%1
81
March1st to 15thDay
24%7%35%26%5%
90
16th to endDay
26%12%20%28%10%2
96
April1st to 15thDay
21%12%26%28%11%
257
16th to endDay
29%8%31%19%8%1
448
May1st to 15thDay
24%10%29%24%8%2
468
16th to endDay
19%6%32%24%12%3
517
June1st to 15thDay
16%6%29%27%17%2
495
16th to endDay
10%6%32%29%16%4
495
July1st to 15thDay
7%5%26%30%22%8%
475
16th to endDay
8%423%36%21%5%
515
August1st to 15thDay
8%320%35%27%5%
493
16th to endDay
14%422%30%21%5%
486
September1st to 15thDay
9%426%35%17%6%
312
16th to endDay
24%432%24%9%4
135
October1st to 15thDay
14%13%35%17%14%5%
135
16th to endDay
24%11%32%18%11%2
144
November1st to 15thDay
16%11%26%33%9%2
135
16th to endDay
24%14%35%21%3
135
December1st to 15thDay
18%7%35%31%6%
90
16th to endDay
32%16%32%16%11
96
January1st to 15thNight
12%12%34%29%9%2
900
16th to endNight
17%11%36%27%7%
960
February1st to 15thNight
12%11%33%31%9%1
880
16th to endNight
12%10%35%29%10%1
789
March1st to 15thNight
15%8%35%30%9%
545
16th to endNight
18%8%32%27%10%2
576
April1st to 15thNight
19%7%35%27%9%
539
16th to endNight
26%7%28%27%8%1
540
May1st to 15thNight
22%8%31%25%10%
540
16th to endNight
14%6%28%35%14%1
563
June1st to 15thNight
15%327%39%13%
540
16th to endNight
8%229%42%16%
540
July1st to 15thNight
7%125%39%24%
510
16th to endNight
5%122%46%21%2
564
August1st to 15thNight
9%116%43%26%2
539
16th to endNight
9%222%37%25%2
573
September1st to 15thNight
9%423%37%22%2
540
16th to endNight
13%6%33%27%17%2
555
October1st to 15thNight
15%8%33%29%11%1
720
16th to endNight
23%8%28%31%7%
768
November1st to 15thNight
16%10%31%30%10%
950
16th to endNight
16%13%33%26%9%
975
December1st to 15thNight
19%9%33%31%6%
905
16th to endNight
25%9%29%28%6%1
960
Page generated at 2017-12-02 08:14:21. Version ac04

Copyright 2017 A. Danko


Cold Spring Clear Sky Chart |Charts Home