Hudson
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hudson clear sky chart from 2005-11-05 to

2017-09-12
.

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
63%
15804
20%
46901
17%
15763
67%
15763
30%
29479

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
48%
718
19%
2327
14%
716
55%
716
25%
1456
January16th to endNight
47%
768
22%
2391
17%
768
54%
768
27%
1507
February1st to 15thNight
51%
701
25%
2103
19%
698
58%
698
33%
1260
February16th to endNight
49%
631
23%
1876
14%
631
58%
631
31%
1153
March1st to 15thNight
56%
720
28%
1980
19%
720
63%
720
39%
1168
March16th to endNight
60%
768
26%
2112
20%
768
63%
768
39%
1236
April1st to 15thNight
66%
718
23%
1976
19%
718
69%
718
42%
1120
April16th to endNight
67%
676
26%
1846
20%
676
70%
676
41%
1073
May1st to 15thNight
76%
539
25%
1619
21%
539
78%
539
43%
877
May16th to endNight
76%
561
23%
1682
20%
561
77%
561
38%
974
June1st to 15thNight
70%
540
13%
1620
12%
540
70%
540
25%
1102
June16th to endNight
76%
540
10%
1620
9%
540
76%
540
23%
1134
July1st to 15thNight
74%
510
7%
1530
7%
510
74%
510
20%
1118
July16th to endNight
77%
564
6%
1595
6%
531
78%
531
20%
1157
August1st to 15thNight
76%
539
4%
1684
5%
536
76%
536
21%
1176
August16th to endNight
70%
675
9%
2012
10%
675
70%
675
21%
1433
September1st to 15thNight
65%
707
8%
1944
7%
707
65%
707
18%
1459
September16th to endNight
64%
657
13%
1815
12%
657
65%
657
22%
1304
October1st to 15thNight
71%
660
26%
1837
26%
660
73%
660
34%
1137
October16th to endNight
62%
704
28%
2112
27%
704
66%
704
33%
1252
November1st to 15thNight
66%
700
30%
2101
29%
700
70%
700
40%
1167
November16th to endNight
57%
720
28%
2283
24%
720
64%
720
33%
1316
December1st to 15thNight
56%
720
25%
2340
25%
720
61%
720
30%
1397
December16th to endNight
57%
768
22%
2496
22%
768
61%
768
29%
1503

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
7%425%6%36%6%7%9%39%
47739
Night
7%425%5%35%5%6%9%44%
47110
TransparencyDay
38%10%15%16%13%5%
47440
Night
33%9%16%19%14%5%
46913
SeeingDay
9%110%20%29%27%
5672
Night
9%215%32%29%10%
15812

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 15thDay
11%6%245%35%36%10%39%
1611
16th to endDay
9%5%2443435%7%48%
1831
February1st to 15thDay
14%5%25%32435%6%46%
1750
16th to endDay
7%5%15%425%35%7%51%
1595
March1st to 15thDay
6%41442445%8%52%
1980
16th to endDay
6%424425%45%8%50%
2111
April1st to 15thDay
6%2145%35%6%6%8%48%
1972
16th to endDay
5%324425%45%9%52%
2121
May1st to 15thDay
5%31342345%9%54%
2331
16th to endDay
6%3146%36%5%7%11%43%
2431
June1st to 15thDay
9%6%26%6%46%7%8%11%30%
2340
16th to endDay
6%436%6%48%7%9%12%29%
2340
July1st to 15thDay
7%5%37%6%48%10%10%12%23%
2340
16th to endDay
5%5%37%8%5%9%10%9%11%22%
2465
August1st to 15thDay
8%5%15%7%5%7%11%11%11%23%
2262
16th to endDay
9%5%27%8%5%7%6%8%13%25%
2175
September1st to 15thDay
8%5%37%8%49%7%10%11%23%
1936
16th to endDay
8%6%47%7%5%7%8%7%10%26%
1815
October1st to 15thDay
6%5%26%6%35%6%6%7%42%
1792
16th to endDay
7%5%245%3445%8%48%
1760
November1st to 15thDay
5%4145%2445%7%53%
1757
16th to endDay
7%425%5%345%5%9%47%
1676
December1st to 15thDay
9%6%25%5%345%5%8%43%
1620
16th to endDay
7%425%435%5%6%8%45%
1728
January1st to 15thNight
12%6%35%4345%6%9%39%
2327
16th to endNight
13%426%5%245%5%7%42%
2391
February1st to 15thNight
10%6%2342345%6%49%
2103
16th to endNight
8%6%25%5%24437%47%
1876
March1st to 15thNight
5%5%25%32445%7%53%
1980
16th to endNight
6%4133245%6%7%54%
2112
April1st to 15thNight
5%32342446%9%53%
1976
16th to endNight
6%313335%35%7%55%
1846
May1st to 15thNight
421342345%10%55%
1619
16th to endNight
4313425%46%10%51%
1682
June1st to 15thNight
9%425%5%46%5%6%10%38%
1620
16th to endNight
6%425%6%36%6%9%12%35%
1620
July1st to 15thNight
4427%6%37%7%9%13%32%
1620
16th to endNight
4436%5%5%9%9%9%13%29%
1703
August1st to 15thNight
44247%5%7%7%10%14%31%
1695
16th to endNight
8%5%25%6%36%7%8%10%34%
2012
September1st to 15thNight
8%5%35%8%47%7%9%10%28%
1944
16th to endNight
9%6%36%8%45%7%8%11%30%
1815
October1st to 15thNight
6%425%4336%5%9%48%
1837
16th to endNight
9%5%25%323447%50%
2112
November1st to 15thNight
5%4243245%5%7%53%
2101
16th to endNight
7%425%43446%8%48%
2283
December1st to 15thNight
10%5%24425%5%49%45%
2340
16th to endNight
8%4345%26%5%6%8%44%
2496

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
38%5%12%19%18%5%
1612
16th to endDay
35%5%9%16%25%8%
1831
February1st to 15thDay
38%48%15%19%14%
1752
16th to endDay
31%7%11%16%22%10%
1595
March1st to 15thDay
27%5%14%23%21%7%
1980
16th to endDay
32%6%11%20%19%9%
2112
April1st to 15thDay
31%8%13%17%21%7%
1972
16th to endDay
29%7%12%20%24%6%
2121
May1st to 15thDay
26%5%16%24%19%7%
2331
16th to endDay
34%9%15%22%16%2
2435
June1st to 15thDay
44%12%19%18%4
2340
16th to endDay
43%17%20%14%3
2340
July1st to 15thDay
48%19%22%8%1
2201
16th to endDay
48%20%20%9%1
2310
August1st to 15thDay
45%20%24%8%
2249
16th to endDay
49%17%20%12%
2175
September1st to 15thDay
51%16%18%10%3
1936
16th to endDay
50%12%14%15%5%2
1815
October1st to 15thDay
37%9%11%15%15%10%
1792
16th to endDay
33%5%10%15%23%11%
1760
November1st to 15thDay
29%5%10%24%21%8%
1757
16th to endDay
32%7%10%18%18%11%
1676
December1st to 15thDay
38%5%13%19%17%4
1620
16th to endDay
34%6%12%21%17%7%
1728
January1st to 15thNight
39%6%13%19%16%4
2327
16th to endNight
39%5%9%16%19%8%
2391
February1st to 15thNight
33%5%8%17%22%12%
2112
16th to endNight
35%6%12%16%21%7%
1876
March1st to 15thNight
30%5%11%27%18%7%
1980
16th to endNight
27%7%11%25%19%8%
2112
April1st to 15thNight
26%5%17%23%21%5%
1976
16th to endNight
26%6%13%23%23%6%
1846
May1st to 15thNight
23%6%15%28%18%6%
1620
16th to endNight
25%9%18%24%17%2
1684
June1st to 15thNight
38%12%21%21%6%
1620
16th to endNight
36%17%22%19%4
1620
July1st to 15thNight
37%20%29%10%2
1530
16th to endNight
37%19%29%11%1
1595
August1st to 15thNight
34%20%35%9%
1684
16th to endNight
40%15%26%15%1
2012
September1st to 15thNight
43%17%23%11%3
1944
16th to endNight
41%13%19%16%6%1
1815
October1st to 15thNight
30%10%12%19%19%8%
1837
16th to endNight
33%5%8%16%25%9%
2112
November1st to 15thNight
27%5%11%22%23%8%
2101
16th to endNight
32%5%10%21%17%12%
2283
December1st to 15thNight
34%6%12%25%15%4
2340
16th to endNight
35%7%13%20%16%7%
2496

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
13%233%24%22%4
90
16th to endDay
16%13%25%27%16%1
96
February1st to 15thDay
8%11%25%22%26%5%
90
16th to endDay
7%7%32%31%19%2
96
March1st to 15thDay
9%325%37%20%2
270
16th to endDay
7%222%31%30%4
288
April1st to 15thDay
8%221%28%33%5%
270
16th to endDay
3114%30%38%11%
270
May1st to 15thDay
7%112%28%30%19%
288
16th to endDay
7%15%15%36%34%
331
June1st to 15thDay
13%15%10%27%41%
315
16th to endDay
5%39%25%55%
315
July1st to 15thDay
5%2422%64%
305
16th to endDay
10%28%25%52%
326
August1st to 15thDay
11%17%21%57%
313
16th to endDay
10%10%26%51%
332
September1st to 15thDay
15%129%32%39%
299
16th to endDay
14%413%34%32%
254
October1st to 15thDay
8%8%26%41%13%
255
16th to endDay
9%212%33%31%10%
272
November1st to 15thDay
5%12%35%35%10%
265
16th to endDay
8%217%39%26%6%
146
December1st to 15thDay
7%131%36%23%
90
16th to endDay
7%114%31%38%7%
96
January1st to 15thNight
14%6%22%34%20%
720
16th to endNight
15%5%25%36%16%
768
February1st to 15thNight
12%5%25%37%17%
704
16th to endNight
9%428%44%13%
631
March1st to 15thNight
7%325%45%15%
720
16th to endNight
8%321%44%19%1
768
April1st to 15thNight
6%317%46%23%1
718
16th to endNight
8%117%41%28%
676
May1st to 15thNight
419%44%34%4
540
16th to endNight
5%8%33%39%11%
563
June1st to 15thNight
12%5%19%44%18%
540
16th to endNight
6%212%40%37%
540
July1st to 15thNight
6%116%39%44%
510
16th to endNight
427%39%44%
564
August1st to 15thNight
6%27%41%40%
539
16th to endNight
10%314%41%29%
675
September1st to 15thNight
10%418%41%23%
707
16th to endNight
11%15%24%44%12%
657
October1st to 15thNight
9%9%36%37%7%
660
16th to endNight
11%215%32%34%3
704
November1st to 15thNight
6%118%44%25%3
700
16th to endNight
9%323%41%20%1
720
December1st to 15thNight
10%322%37%24%
720
16th to endNight
10%420%36%26%1
768
Page generated at 2017-09-13 07:39:09. Version ac04

Copyright 2017 A. Danko


Hudson Clear Sky Chart | Charts Home