Hudson
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hudson clear sky chart from 2005-11-06 to 2024-01-14.

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
32%
22549
14%
74728
9%
22513
39%
22513
17%
52745

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
19%
760
9%
2649
5%
757
25%
757
9%
2087
January11th to 20thNight
20%
735
10%
2569
5%
735
26%
735
11%
1996
January21st to endNight
25%
792
13%
2772
8%
792
33%
792
14%
1985
February1st to 10thNight
19%
720
10%
2354
5%
720
27%
720
11%
1827
February11th to 20thNight
24%
702
13%
2198
7%
700
33%
700
16%
1582
February21st to endNight
25%
592
16%
1776
7%
592
36%
592
16%
1297
March1st to 10thNight
25%
720
15%
2160
10%
720
31%
720
15%
1606
March11th to 20thNight
26%
720
15%
2070
7%
720
34%
720
18%
1496
March21st to endNight
33%
792
21%
1998
9%
792
40%
792
24%
1439
April1st to 10thNight
30%
720
16%
1800
5%
720
36%
720
20%
1344
April11th to 20thNight
31%
711
16%
1775
5%
711
37%
711
23%
1298
April21st to endNight
31%
594
17%
1674
8%
594
37%
594
19%
1194
May1st to 10thNight
34%
391
16%
1471
13%
391
43%
391
17%
980
May11th to 20thNight
36%
354
19%
1416
18%
354
48%
354
18%
901
May21st to endNight
39%
388
14%
1551
14%
388
49%
388
21%
947
June1st to 10thNight
38%
360
10%
1440
11%
360
47%
360
17%
977
June11th to 20thNight
43%
360
12%
1440
15%
360
51%
360
21%
875
June21st to endNight
41%
360
10%
1440
13%
360
48%
360
18%
923
July1st to 10thNight
55%
350
14%
1400
19%
350
63%
350
25%
804
July11th to 20thNight
52%
348
15%
1392
21%
348
58%
348
24%
799
July21st to endNight
54%
394
15%
1486
18%
372
58%
372
24%
860
August1st to 10thNight
59%
358
17%
1422
20%
356
62%
356
25%
804
August11th to 20thNight
53%
541
18%
1605
13%
541
57%
541
29%
1012
August21st to endNight
51%
792
18%
1980
9%
792
54%
792
34%
1320
September1st to 10thNight
51%
720
16%
1800
8%
720
54%
720
31%
1214
September11th to 20thNight
52%
720
21%
1859
13%
720
55%
720
35%
1180
September21st to endNight
46%
720
21%
1980
15%
720
51%
720
27%
1302
October1st to 10thNight
37%
720
18%
2123
12%
720
46%
720
21%
1466
October11th to 20thNight
33%
720
16%
2179
10%
720
40%
720
19%
1537
October21st to endNight
27%
792
12%
2574
8%
792
33%
792
15%
1876
November1st to 10thNight
29%
740
16%
2407
9%
740
38%
740
17%
1670
November11th to 20thNight
24%
760
17%
2564
10%
760
34%
760
16%
1810
November21st to endNight
20%
760
12%
2660
5%
760
28%
760
10%
2005
December1st to 10thNight
18%
760
9%
2660
4%
760
24%
760
9%
2103
December11th to 20thNight
18%
760
12%
3247
6%
759
27%
759
8%
2476
December21st to endNight
16%
823
6%
4837
4%
817
24%
817
6%
3753

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%9%37%6%35%5%5%7%33%
74768
Night
18%10%47%6%35%45%6%32%
74987
TransparencyDay
50%5%12%21%11%1
74473
Night
53%5%11%20%11%1
74816
SeeingDay
21%9%27%26%13%4
13446
Night
23%8%28%30%11%1
22564

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
18%19%6%10%8%35%345%21%
1517
11th to 20thDay
20%15%6%9%5%34445%25%
1464
21st to endDay
11%15%6%7%7%46%5%5%6%27%
1584
February1st to 10thDay
15%15%5%11%6%45%5%5%5%24%
1603
11th to 20thDay
15%12%5%8%7%5%5%5%47%27%
1649
21st to endDay
19%13%6%9%7%35%445%26%
1480
March1st to 10thDay
16%12%49%7%35%445%30%
1797
11th to 20thDay
16%11%47%7%45%46%6%31%
1886
21st to endDay
20%8%47%5%3445%5%35%
2358
April1st to 10thDay
21%9%46%7%34446%32%
2160
11th to 20thDay
20%8%36%5%3445%5%36%
2134
21st to endDay
22%9%36%5%45%5%5%5%31%
2286
May1st to 10thDay
19%7%46%5%35%5%5%6%34%
2505
11th to 20thDay
17%8%36%5%35%45%7%38%
2478
21st to endDay
17%7%35%6%36%5%6%7%37%
2725
June1st to 10thDay
21%7%36%6%35%5%6%7%30%
2520
11th to 20thDay
15%6%26%6%35%5%6%9%38%
2520
21st to endDay
18%8%36%6%36%5%6%8%31%
2520
July1st to 10thDay
12%5%36%5%36%5%6%8%42%
2520
11th to 20thDay
13%5%25%6%45%7%7%10%37%
2520
21st to endDay
12%5%25%6%46%6%7%10%37%
2744
August1st to 10thDay
12%6%26%6%36%6%7%8%38%
2506
11th to 20thDay
10%5%36%6%45%6%7%9%41%
2274
21st to endDay
13%5%25%5%35%6%6%9%41%
2376
September1st to 10thDay
12%6%25%5%35%5%6%8%42%
2160
11th to 20thDay
13%6%2442445%7%48%
2100
21st to endDay
16%6%25%6%3446%7%41%
1980
October1st to 10thDay
21%6%37%5%3445%7%36%
1836
11th to 20thDay
19%9%38%7%46%5%46%28%
1780
21st to endDay
25%11%35%5%2446%6%27%
1782
November1st to 10thDay
16%9%37%5%35%5%6%7%33%
1671
11th to 20thDay
18%9%48%5%45%5%5%7%28%
1615
21st to endDay
22%9%38%6%5%6%6%46%23%
1520
December1st to 10thDay
25%14%6%7%7%45%5%5%5%19%
1520
11th to 20thDay
22%12%5%8%6%4445%5%25%
1906
21st to endDay
28%16%5%8%6%3333420%
2772
January1st to 10thNight
18%18%6%9%7%45%45%5%19%
2649
11th to 20thNight
19%17%6%9%7%3444423%
2569
21st to endNight
12%13%6%9%8%46%446%30%
2772
February1st to 10thNight
15%13%6%10%8%46%5%6%6%21%
2354
11th to 20thNight
15%10%49%7%36%5%5%6%28%
2196
21st to endNight
16%13%6%9%5%445%4431%
1776
March1st to 10thNight
17%12%5%9%6%35%45%6%28%
2150
11th to 20thNight
17%13%46%6%3445%5%32%
2069
21st to endNight
17%11%37%43444438%
1998
April1st to 10thNight
24%9%36%5%35%446%31%
1800
11th to 20thNight
22%7%36%5%34446%34%
1775
21st to endNight
21%9%36%6%34447%33%
1674
May1st to 10thNight
21%8%26%6%3445%6%35%
1471
11th to 20thNight
18%7%46%5%35%45%5%40%
1415
21st to endNight
16%5%35%6%345%48%41%
1550
June1st to 10thNight
20%7%26%446%5%6%8%31%
1440
11th to 20thNight
16%7%35%5%36%45%7%40%
1440
21st to endNight
17%6%36%5%35%6%6%8%36%
1440
July1st to 10thNight
10%5%25%5%45%6%5%8%45%
1440
11th to 20thNight
11%5%25%6%35%5%6%10%41%
1440
21st to endNight
11%6%35%5%35%6%6%9%42%
1574
August1st to 10thNight
11%6%25%435%5%6%9%44%
1432
11th to 20thNight
12%5%35%5%35%5%5%6%45%
1605
21st to endNight
13%5%25%435%5%7%8%42%
1980
September1st to 10thNight
12%6%36%6%45%46%7%42%
1800
11th to 20thNight
16%5%25%423437%49%
1859
21st to endNight
16%6%2443445%7%43%
1980
October1st to 10thNight
18%6%27%5%45%5%5%7%37%
2123
11th to 20thNight
20%8%37%6%35%5%46%33%
2179
21st to endNight
23%8%48%7%35%5%45%29%
2574
November1st to 10thNight
19%9%36%6%35%45%7%33%
2407
11th to 20thNight
19%9%47%6%35%5%5%5%32%
2564
21st to endNight
22%11%48%6%35%5%46%26%
2660
December1st to 10thNight
22%14%6%8%6%45%45%5%21%
2660
11th to 20thNight
23%14%5%7%6%345%4425%
3288
21st to endNight
30%16%48%5%2334421%
4884

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
66%49%16%5%
1518
11th to 20thDay
62%49%13%11%1
1464
21st to endDay
56%6%11%17%9%1
1584
February1st to 10thDay
61%49%19%5%2
1603
11th to 20thDay
56%413%17%8%1
1658
21st to endDay
61%39%15%9%2
1480
March1st to 10thDay
57%310%18%10%2
1800
11th to 20thDay
52%313%16%13%3
1886
21st to endDay
50%310%19%14%4
2358
April1st to 10thDay
53%5%7%21%12%2
2160
11th to 20thDay
48%38%23%16%2
2134
21st to endDay
54%39%18%13%4
2286
May1st to 10thDay
49%5%8%21%15%2
2505
11th to 20thDay
45%410%22%16%3
2482
21st to endDay
45%5%13%21%14%2
2725
June1st to 10thDay
51%5%11%20%12%1
2520
11th to 20thDay
43%5%11%23%14%3
2520
21st to endDay
50%5%14%19%10%1
2520
July1st to 10thDay
37%6%15%28%14%1
2450
11th to 20thDay
39%5%17%28%10%
2445
21st to endDay
40%6%17%27%9%
2591
August1st to 10thDay
41%6%18%27%9%
2492
11th to 20thDay
37%6%19%27%10%1
2274
21st to endDay
37%6%15%28%14%1
2376
September1st to 10thDay
38%6%15%28%13%
2160
11th to 20thDay
36%412%32%15%1
2100
21st to endDay
42%5%14%28%10%1
1980
October1st to 10thDay
49%5%11%23%11%
1836
11th to 20thDay
55%414%19%7%
1780
21st to endDay
56%5%13%18%8%1
1782
November1st to 10thDay
48%5%16%22%8%1
1671
11th to 20thDay
55%5%12%19%10%
1615
21st to endDay
60%6%13%16%5%1
1520
December1st to 10thDay
68%5%11%13%4
1520
11th to 20thDay
61%6%12%16%5%
1906
21st to endDay
70%310%12%5%
2772
January1st to 10thNight
66%49%15%5%
2649
11th to 20thNight
64%410%14%7%1
2569
21st to endNight
56%410%17%11%1
2772
February1st to 10thNight
62%6%9%16%6%1
2354
11th to 20thNight
54%5%12%21%8%1
2198
21st to endNight
56%38%18%14%1
1776
March1st to 10thNight
58%49%17%11%2
2160
11th to 20thNight
54%410%17%13%3
2070
21st to endNight
50%36%21%15%4
1998
April1st to 10thNight
54%48%19%14%2
1800
11th to 20thNight
51%47%21%15%2
1775
21st to endNight
52%47%19%13%4
1674
May1st to 10thNight
50%46%18%16%5%
1471
11th to 20thNight
47%47%19%19%4
1416
21st to endNight
43%413%21%17%2
1551
June1st to 10thNight
51%5%10%21%11%1
1440
11th to 20thNight
43%5%12%23%16%2
1440
21st to endNight
46%6%14%20%14%
1440
July1st to 10thNight
36%6%13%27%18%1
1400
11th to 20thNight
37%6%14%30%12%
1392
21st to endNight
37%6%17%27%12%
1486
August1st to 10thNight
36%6%19%27%11%
1422
11th to 20thNight
39%5%17%25%13%
1605
21st to endNight
38%5%16%28%12%1
1980
September1st to 10thNight
40%6%11%27%16%1
1800
11th to 20thNight
37%313%34%12%1
1859
21st to endNight
41%6%11%28%14%
1980
October1st to 10thNight
47%6%9%24%12%1
2123
11th to 20thNight
52%411%24%9%
2179
21st to endNight
57%413%17%8%1
2574
November1st to 10thNight
52%412%22%9%1
2407
11th to 20thNight
53%5%13%18%10%1
2564
21st to endNight
61%5%11%16%6%
2660
December1st to 10thNight
66%5%11%15%4
2660
11th to 20thNight
63%5%8%17%6%
3288
21st to endNight
68%49%15%4
4884

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
23%12%28%25%11%1
180
11th to 20thDay
30%11%30%22%7%1
166
21st to endDay
19%11%36%22%10%1
176
February1st to 10thDay
31%18%35%14%3
233
11th to 20thDay
24%8%42%23%3
316
21st to endDay
29%9%29%29%3
346
March1st to 10thDay
23%10%35%25%8%
420
11th to 20thDay
20%12%35%24%7%2
420
21st to endDay
25%9%29%20%14%2
462
April1st to 10thDay
27%12%26%24%11%2
420
11th to 20thDay
25%12%26%22%12%3
412
21st to endDay
27%11%27%23%10%2
420
May1st to 10thDay
21%9%30%26%11%3
423
11th to 20thDay
19%6%32%25%14%4
447
21st to endDay
18%8%30%26%13%5%
485
June1st to 10thDay
22%8%24%29%13%4
450
11th to 20thDay
17%7%24%31%18%3
450
21st to endDay
21%6%25%27%16%5%
450
July1st to 10thDay
11%7%23%31%21%7%
445
11th to 20thDay
13%426%31%19%6%
444
21st to endDay
13%6%21%35%19%5%
488
August1st to 10thDay
15%421%30%22%8%
446
11th to 20thDay
11%421%33%21%10%
439
21st to endDay
14%7%25%24%21%9%
495
September1st to 10thDay
15%6%23%26%19%10%
450
11th to 20thDay
14%7%23%25%20%12%
450
21st to endDay
18%8%25%23%20%7%
450
October1st to 10thDay
22%8%25%25%14%6%
450
11th to 20thDay
20%12%30%23%14%2
439
21st to endDay
30%12%24%24%9%
396
November1st to 10thDay
26%13%23%28%9%1
365
11th to 20thDay
23%15%33%20%8%1
275
21st to endDay
25%14%33%21%7%1
180
December1st to 10thDay
32%8%27%24%8%1
180
11th to 20thDay
24%13%39%17%6%1
180
21st to endDay
32%13%29%18%6%2
198
January1st to 10thNight
25%12%30%28%5%
760
11th to 20thNight
28%8%33%25%5%1
735
21st to endNight
19%9%35%29%8%1
792
February1st to 10thNight
21%10%36%25%6%1
720
11th to 20thNight
21%10%35%29%5%
703
21st to endNight
22%9%34%29%5%
592
March1st to 10thNight
23%11%31%29%6%
720
11th to 20thNight
25%10%31%28%7%1
720
21st to endNight
23%7%28%32%10%1
792
April1st to 10thNight
27%10%26%31%6%
720
11th to 20thNight
24%10%29%29%7%1
711
21st to endNight
27%9%26%28%10%
594
May1st to 10thNight
24%6%29%30%10%2
391
11th to 20thNight
21%6%28%34%10%1
354
21st to endNight
16%5%31%38%11%
389
June1st to 10thNight
26%327%33%11%1
360
11th to 20thNight
18%5%26%35%16%1
360
21st to endNight
18%5%26%33%18%1
360
July1st to 10thNight
12%423%40%20%1
350
11th to 20thNight
11%324%44%17%1
348
21st to endNight
13%422%43%17%2
394
August1st to 10thNight
15%315%45%22%1
358
11th to 20thNight
14%220%36%24%3
541
21st to endNight
15%322%34%23%3
792
September1st to 10thNight
14%422%40%19%1
720
11th to 20thNight
19%5%18%35%21%2
720
21st to endNight
19%6%23%30%19%3
720
October1st to 10thNight
21%7%27%31%14%1
720
11th to 20thNight
23%8%28%29%11%1
720
21st to endNight
27%9%30%28%6%
792
November1st to 10thNight
25%11%28%27%9%1
740
11th to 20thNight
23%13%33%20%9%1
760
21st to endNight
29%12%29%21%8%1
760
December1st to 10thNight
31%11%30%23%5%
760
11th to 20thNight
29%13%29%23%5%1
760
21st to endNight
35%11%27%22%5%
836
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