This page made possible by the sponsorship of:
, Teach English in China,
.

New York City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the New York City clear sky chart from 2005-11-05 to 2018-03-11.

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
35%
15737
20%
49102
11%
15706
46%
15706
24%
31216

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
24%
780
21%
2716
9%
776
40%
776
20%
1692
January16th to endNight
21%
832
22%
2811
8%
832
39%
832
21%
1754
February1st to 15thNight
19%
764
18%
2409
5%
761
35%
761
20%
1593
February16th to endNight
22%
683
26%
2049
10%
683
42%
683
23%
1309
March1st to 15thNight
23%
764
19%
2288
8%
764
37%
764
23%
1495
March16th to endNight
27%
768
23%
1991
9%
768
39%
768
26%
1324
April1st to 15thNight
29%
718
17%
1796
6%
718
35%
718
27%
1235
April16th to endNight
32%
705
18%
1785
6%
705
38%
705
27%
1221
May1st to 15thNight
30%
509
18%
1589
8%
509
40%
509
21%
1061
May16th to endNight
47%
374
16%
1497
15%
374
54%
374
20%
917
June1st to 15thNight
45%
360
15%
1440
13%
360
54%
360
19%
906
June16th to endNight
59%
360
15%
1440
19%
360
64%
360
27%
805
July1st to 15thNight
54%
340
13%
1360
16%
340
57%
340
21%
810
July16th to endNight
59%
376
17%
1418
18%
354
65%
354
25%
814
August1st to 15thNight
58%
563
19%
1634
14%
561
61%
561
31%
1005
August16th to endNight
60%
764
19%
1910
11%
764
62%
764
33%
1274
September1st to 15thNight
50%
720
23%
1800
13%
720
53%
720
34%
1177
September16th to endNight
52%
717
26%
1974
20%
717
57%
717
33%
1237
October1st to 15thNight
43%
720
21%
2102
16%
720
50%
720
26%
1338
October16th to endNight
32%
768
24%
2400
13%
768
47%
768
26%
1473
November1st to 15thNight
34%
760
22%
2472
12%
760
48%
760
24%
1521
November16th to endNight
29%
780
22%
2579
12%
780
43%
780
23%
1594
December1st to 15thNight
26%
780
16%
2730
7%
780
38%
780
18%
1786
December16th to endNight
19%
832
20%
2912
6%
832
37%
832
18%
1875

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
15%5%2442445%7%41%
49536
Night
16%6%24424446%43%
49272
Cloud CoverDay
16%5%2442445%7%41%
49545
Night
16%6%24424446%42%
49278
TransparencyDay
41%5%11%23%16%2
49224
Night
41%411%22%16%2
49102
SeeingDay
19%8%28%25%14%3
6332
Night
19%8%30%29%11%1
15738

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
15%6%2443446%6%43%
1552
16th to endDay
15%6%34434346%43%
1763
February1st to 15thDay
16%7%35%5%24345%41%
1780
16th to endDay
17%5%25%42435%7%40%
1710
March1st to 15thDay
17%6%25%5%2445%7%38%
1898
16th to endDay
17%6%34323445%43%
2232
April1st to 15thDay
19%5%34314347%42%
2152
16th to endDay
16%425%43435%7%43%
2175
May1st to 15thDay
21%5%25%424447%35%
2373
16th to endDay
17%5%2442445%8%38%
2618
June1st to 15thDay
18%6%344245%5%8%37%
2520
16th to endDay
11%5%25%435%5%6%8%40%
2520
July1st to 15thDay
10%425%5%36%5%7%10%37%
2520
16th to endDay
10%426%5%26%6%7%9%38%
2654
August1st to 15thDay
10%5%15%5%35%5%7%7%41%
2301
16th to endDay
12%5%245%3445%8%43%
2292
September1st to 15thDay
14%413425%446%47%
2160
16th to endDay
14%5%245%23446%45%
1986
October1st to 15thDay
16%5%245%33447%42%
1857
16th to endDay
19%414423347%45%
1824
November1st to 15thDay
19%5%24423435%45%
1716
16th to endDay
15%423424346%46%
1709
December1st to 15thDay
17%7%25%423436%41%
1560
16th to endDay
20%7%25%423346%38%
1664
January1st to 15thNight
18%5%23433445%43%
2716
16th to endNight
16%8%33424336%42%
2811
February1st to 15thNight
15%8%35%5%23445%40%
2408
16th to endNight
17%6%24333445%45%
2049
March1st to 15thNight
19%6%2432335%5%42%
2275
16th to endNight
17%7%24313445%44%
1991
April1st to 15thNight
18%5%2442445%7%39%
1796
16th to endNight
18%5%24425%346%42%
1785
May1st to 15thNight
18%7%25%6%23336%39%
1589
16th to endNight
18%5%24433448%40%
1495
June1st to 15thNight
18%5%34325%45%7%39%
1440
16th to endNight
8%424425%5%5%10%44%
1440
July1st to 15thNight
11%425%435%5%7%9%40%
1440
16th to endNight
8%5%235%36%6%6%9%41%
1514
August1st to 15thNight
10%3245%336%6%9%45%
1644
16th to endNight
12%425%5%345%5%8%42%
1910
September1st to 15thNight
15%414424447%46%
1800
16th to endNight
12%6%24413336%49%
1974
October1st to 15thNight
16%5%2442335%6%44%
2102
16th to endNight
17%5%24322345%48%
2400
November1st to 15thNight
16%6%24423335%47%
2472
16th to endNight
17%5%2442345%6%42%
2579
December1st to 15thNight
21%6%25%424445%37%
2730
16th to endNight
18%6%24424446%40%
2912

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
15%6%2342435%6%43%
1552
16th to endDay
15%7%34423346%43%
1763
February1st to 15thDay
16%6%26%424336%40%
1780
16th to endDay
17%5%35%424446%41%
1710
March1st to 15thDay
17%6%3442435%7%39%
1908
16th to endDay
18%6%34424345%42%
2231
April1st to 15thDay
19%6%34313347%41%
2152
16th to endDay
16%42442445%7%43%
2175
May1st to 15thDay
21%5%25%43436%7%35%
2373
16th to endDay
18%42443445%9%38%
2618
June1st to 15thDay
19%6%235%135%6%9%36%
2520
16th to endDay
11%425%5%45%5%5%9%41%
2520
July1st to 15thDay
10%425%5%36%5%6%9%38%
2520
16th to endDay
10%5%25%5%35%6%7%8%39%
2654
August1st to 15thDay
11%4245%346%6%9%41%
2301
16th to endDay
12%5%245%345%5%8%44%
2292
September1st to 15thDay
14%324424446%47%
2160
16th to endDay
14%415%434447%45%
1986
October1st to 15thDay
16%5%245%3435%6%42%
1857
16th to endDay
18%424324346%46%
1824
November1st to 15thDay
18%5%24323345%45%
1716
16th to endDay
15%424323437%46%
1709
December1st to 15thDay
16%8%25%423446%41%
1560
16th to endDay
21%7%245%23346%38%
1664
January1st to 15thNight
18%5%24423346%43%
2716
16th to endNight
17%8%33314445%43%
2811
February1st to 15thNight
15%8%35%5%34336%40%
2401
16th to endNight
18%5%34324335%44%
2049
March1st to 15thNight
19%6%25%313346%42%
2288
16th to endNight
17%7%24323335%44%
1991
April1st to 15thNight
17%6%25%42345%7%39%
1796
16th to endNight
18%6%24424437%42%
1785
May1st to 15thNight
19%6%35%5%23446%39%
1589
16th to endNight
18%6%245%23448%40%
1495
June1st to 15thNight
19%5%24234447%39%
1440
16th to endNight
8%425%43447%10%44%
1440
July1st to 15thNight
11%425%5%35%46%10%39%
1440
16th to endNight
9%4145%45%6%6%10%40%
1514
August1st to 15thNight
10%423435%5%5%8%45%
1644
16th to endNight
13%424425%46%7%43%
1910
September1st to 15thNight
14%414434447%46%
1800
16th to endNight
12%6%25%423336%48%
1974
October1st to 15thNight
17%5%24423346%45%
2102
16th to endNight
18%5%24322246%47%
2400
November1st to 15thNight
16%6%24423335%47%
2472
16th to endNight
17%5%24423446%42%
2579
December1st to 15thNight
21%6%35%42445%6%37%
2730
16th to endNight
19%6%25%42445%5%40%
2912

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
40%313%24%13%3
1553
16th to endDay
42%212%25%13%2
1763
February1st to 15thDay
45%411%23%13%2
1783
16th to endDay
43%49%26%14%1
1710
March1st to 15thDay
44%414%22%11%2
1908
16th to endDay
43%410%20%18%3
2232
April1st to 15thDay
43%310%24%14%4
2152
16th to endDay
39%5%9%21%21%3
2175
May1st to 15thDay
47%49%20%15%1
2373
16th to endDay
42%6%14%21%13%1
2622
June1st to 15thDay
44%6%12%23%12%
2520
16th to endDay
38%7%12%25%14%1
2520
July1st to 15thDay
39%8%11%21%17%1
2371
16th to endDay
36%8%14%24%13%2
2487
August1st to 15thDay
37%7%14%21%17%
2287
16th to endDay
37%5%10%24%20%2
2292
September1st to 15thDay
36%6%11%22%22%1
2160
16th to endDay
39%38%22%23%2
1986
October1st to 15thDay
41%411%22%18%1
1857
16th to endDay
38%49%27%17%2
1824
November1st to 15thDay
41%313%20%19%2
1716
16th to endDay
38%211%27%15%2
1709
December1st to 15thDay
44%415%20%14%1
1560
16th to endDay
46%414%20%13%
1664
January1st to 15thNight
42%410%23%15%3
2716
16th to endNight
43%310%24%16%1
2811
February1st to 15thNight
45%411%21%14%2
2409
16th to endNight
41%38%24%18%3
2049
March1st to 15thNight
44%312%22%13%3
2288
16th to endNight
42%49%21%17%4
1991
April1st to 15thNight
43%410%21%16%3
1796
16th to endNight
43%48%18%22%2
1785
May1st to 15thNight
46%410%17%17%2
1589
16th to endNight
43%415%19%14%2
1497
June1st to 15thNight
44%5%12%19%17%
1440
16th to endNight
33%6%15%27%15%1
1440
July1st to 15thNight
39%7%13%23%14%2
1360
16th to endNight
34%8%15%25%13%3
1418
August1st to 15thNight
35%6%12%26%16%2
1634
16th to endNight
38%5%12%22%19%1
1910
September1st to 15thNight
38%411%25%18%1
1800
16th to endNight
37%47%22%26%1
1974
October1st to 15thNight
40%411%23%17%2
2102
16th to endNight
39%311%25%18%1
2400
November1st to 15thNight
40%310%21%19%4
2472
16th to endNight
41%310%27%14%2
2579
December1st to 15thNight
47%314%20%12%1
2730
16th to endNight
45%412%22%14%1
2912

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
16%22%36%18%5%
90
16th to endDay
21%10%44%20%4
119
February1st to 15thDay
22%19%36%18%2
206
16th to endDay
21%12%41%20%4
291
March1st to 15thDay
20%16%34%24%4
312
16th to endDay
21%11%38%19%7%1
288
April1st to 15thDay
22%8%36%18%11%2
270
16th to endDay
21%8%32%22%11%3
270
May1st to 15thDay
30%10%25%21%8%3
288
16th to endDay
23%325%25%19%2
331
June1st to 15thDay
18%8%27%26%14%4
315
16th to endDay
15%429%30%18%1
315
July1st to 15thDay
12%223%34%21%5%
305
16th to endDay
13%319%31%25%5%
326
August1st to 15thDay
15%218%32%23%7%
313
16th to endDay
13%115%36%24%9%
332
September1st to 15thDay
15%329%25%19%7%
315
16th to endDay
19%421%23%18%13%
314
October1st to 15thDay
22%319%30%18%5%
315
16th to endDay
17%11%31%27%10%1
312
November1st to 15thDay
22%10%26%26%14%1
280
16th to endDay
15%15%35%24%8%1
239
December1st to 15thDay
18%20%36%15%7%1
90
16th to endDay
31%18%38%10%1
96
January1st to 15thNight
20%13%37%25%3
780
16th to endNight
22%13%37%23%2
832
February1st to 15thNight
19%12%41%23%1
764
16th to endNight
19%14%39%23%2
683
March1st to 15thNight
22%11%38%22%4
764
16th to endNight
20%9%36%25%5%
768
April1st to 15thNight
21%8%36%28%5%
718
16th to endNight
20%8%34%28%7%
705
May1st to 15thNight
20%7%33%28%9%
509
16th to endNight
20%322%38%13%1
375
June1st to 15thNight
20%6%21%35%16%
360
16th to endNight
9%121%49%16%
360
July1st to 15thNight
12%220%42%20%1
340
16th to endNight
10%218%42%23%2
376
August1st to 15thNight
13%117%43%22%1
563
16th to endNight
14%113%37%29%3
764
September1st to 15thNight
17%323%34%19%2
720
16th to endNight
15%318%33%23%5%
717
October1st to 15thNight
19%7%22%29%17%3
720
16th to endNight
20%9%32%26%9%
768
November1st to 15thNight
18%9%30%25%14%
760
16th to endNight
18%11%33%26%8%
780
December1st to 15thNight
24%9%34%22%7%1
780
16th to endNight
23%12%40%21%2
832
Page generated at 2018-03-12 13:28:05. Version ac04

Copyright 2018 A. Danko


New York City Clear Sky Chart |Charts Home