Clarence Fahnestock Memorial State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Clarence Fahnestock Memorial State Park clear sky chart from 2005-11-05 to 2018-03-21.

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
30%
15708
19%
49213
9%
15677
42%
15677
22%
31463

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
21%
780
20%
2716
8%
776
37%
776
19%
1671
January16th to endNight
20%
832
20%
2837
6%
832
39%
832
18%
1760
February1st to 15thNight
15%
764
17%
2416
3%
761
31%
761
16%
1607
February16th to endNight
18%
683
23%
2049
8%
683
38%
683
19%
1316
March1st to 15thNight
18%
780
18%
2340
6%
780
32%
780
18%
1549
March16th to endNight
21%
792
25%
2058
7%
792
35%
792
22%
1355
April1st to 15thNight
22%
718
17%
1796
4%
718
29%
718
21%
1264
April16th to endNight
24%
687
18%
1767
4%
687
33%
687
24%
1210
May1st to 15thNight
25%
496
18%
1576
8%
496
35%
496
19%
1043
May16th to endNight
39%
374
15%
1497
12%
374
47%
374
19%
922
June1st to 15thNight
39%
360
13%
1440
10%
360
50%
360
18%
908
June16th to endNight
50%
360
14%
1440
15%
360
59%
360
26%
810
July1st to 15thNight
50%
340
13%
1360
16%
340
54%
340
22%
815
July16th to endNight
53%
376
15%
1418
18%
354
59%
354
23%
843
August1st to 15thNight
52%
525
18%
1596
12%
523
57%
523
30%
971
August16th to endNight
56%
764
18%
1910
10%
764
58%
764
32%
1290
September1st to 15thNight
44%
720
23%
1800
11%
720
49%
720
34%
1166
September16th to endNight
49%
717
27%
1977
18%
717
55%
717
34%
1203
October1st to 15thNight
37%
720
21%
2097
13%
720
46%
720
26%
1338
October16th to endNight
28%
768
20%
2415
10%
768
42%
768
23%
1552
November1st to 15thNight
31%
760
21%
2472
10%
760
46%
760
23%
1537
November16th to endNight
26%
780
22%
2594
11%
780
41%
780
20%
1621
December1st to 15thNight
24%
780
16%
2730
6%
780
36%
780
15%
1806
December16th to endNight
16%
832
18%
2912
4%
832
33%
832
15%
1906

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
16%6%25%42445%7%39%
49640
Night
16%6%25%42445%6%40%
49383
Cloud CoverDay
16%6%25%43445%7%39%
49649
Night
16%6%2442445%6%41%
49389
TransparencyDay
43%411%22%14%1
49328
Night
42%412%23%15%1
49213
SeeingDay
21%13%27%22%11%3
6340
Night
20%13%30%25%9%
15709

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
14%6%35%5%35%45%5%40%
1552
16th to endDay
14%8%26%43445%6%39%
1736
February1st to 15thDay
16%8%36%6%34448%34%
1773
16th to endDay
17%6%25%425%447%38%
1710
March1st to 15thDay
17%8%35%6%2445%7%33%
1940
16th to endDay
17%7%25%5%24445%40%
2291
April1st to 15thDay
20%6%35%423445%38%
2152
16th to endDay
17%6%24423446%43%
2193
May1st to 15thDay
21%7%35%42445%6%34%
2385
16th to endDay
16%6%35%5%245%5%7%36%
2618
June1st to 15thDay
22%425%325%5%6%7%33%
2520
16th to endDay
12%426%5%35%5%6%8%36%
2520
July1st to 15thDay
11%6%25%5%36%5%5%9%37%
2520
16th to endDay
12%425%6%36%6%6%9%36%
2654
August1st to 15thDay
13%6%245%36%5%6%8%38%
2339
16th to endDay
11%5%244345%5%8%43%
2292
September1st to 15thDay
13%5%25%4345%46%42%
2160
16th to endDay
12%425%5%24447%47%
1983
October1st to 15thDay
18%6%24424436%42%
1860
16th to endDay
18%5%245%3445%5%40%
1809
November1st to 15thDay
18%5%14423346%43%
1716
16th to endDay
17%6%33424336%44%
1693
December1st to 15thDay
17%7%46%5%34346%37%
1560
16th to endDay
19%8%44425%45%7%33%
1664
January1st to 15thNight
15%6%25%424446%41%
2716
16th to endNight
15%8%35%42435%6%40%
2837
February1st to 15thNight
15%8%36%5%3445%5%37%
2415
16th to endNight
16%6%26%42445%6%40%
2049
March1st to 15thNight
19%6%25%43346%6%37%
2327
16th to endNight
16%6%34323446%43%
2058
April1st to 15thNight
18%7%25%5%35%446%35%
1796
16th to endNight
17%6%25%423445%42%
1767
May1st to 15thNight
18%6%25%6%2445%6%35%
1576
16th to endNight
16%5%1343445%8%39%
1495
June1st to 15thNight
20%42442445%8%37%
1440
16th to endNight
10%425%42446%10%43%
1440
July1st to 15thNight
12%6%25%43447%7%40%
1440
16th to endNight
10%5%25%5%26%6%6%9%40%
1514
August1st to 15thNight
11%415%325%5%6%7%45%
1606
16th to endNight
13%415%43446%6%43%
1910
September1st to 15thNight
15%413424345%48%
1800
16th to endNight
12%5%23323336%52%
1977
October1st to 15thNight
16%7%35%323435%45%
2097
16th to endNight
18%5%25%434346%40%
2415
November1st to 15thNight
15%7%24423446%43%
2472
16th to endNight
16%6%35%5%33446%41%
2594
December1st to 15thNight
19%8%25%5%24446%35%
2730
16th to endNight
19%8%25%4235%5%7%34%
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
14%6%245%3445%6%41%
1552
16th to endDay
14%8%25%42445%7%39%
1736
February1st to 15thDay
16%8%36%6%2345%7%35%
1773
16th to endDay
17%7%15%334446%39%
1710
March1st to 15thDay
18%7%35%6%245%5%8%33%
1950
16th to endDay
17%8%35%5%23436%40%
2290
April1st to 15thDay
20%7%34323445%39%
2152
16th to endDay
17%5%244235%46%43%
2193
May1st to 15thDay
22%6%25%5%24447%33%
2385
16th to endDay
17%6%26%4345%5%7%36%
2618
June1st to 15thDay
22%4344245%6%7%33%
2520
16th to endDay
12%5%25%6%35%6%5%8%36%
2520
July1st to 15thDay
12%5%25%5%36%5%6%8%37%
2520
16th to endDay
12%5%25%5%36%6%7%8%36%
2654
August1st to 15thDay
13%6%246%345%7%8%38%
2339
16th to endDay
12%5%25%435%45%8%42%
2292
September1st to 15thDay
14%5%15%5%3445%7%42%
2160
16th to endDay
12%425%5%3335%6%46%
1983
October1st to 15thDay
19%6%24424435%42%
1860
16th to endDay
18%5%25%425%45%5%40%
1809
November1st to 15thDay
19%5%14323346%44%
1716
16th to endDay
18%6%23324345%44%
1693
December1st to 15thDay
18%7%36%435%345%37%
1560
16th to endDay
20%8%3442445%6%34%
1664
January1st to 15thNight
16%6%2442345%6%42%
2716
16th to endNight
15%8%35%33335%6%41%
2837
February1st to 15thNight
14%8%35%5%34446%38%
2408
16th to endNight
16%6%35%42445%5%41%
2049
March1st to 15thNight
20%6%2442445%7%38%
2340
16th to endNight
16%6%35%424346%44%
2058
April1st to 15thNight
18%7%245%3445%6%36%
1796
16th to endNight
18%6%25%323445%41%
1767
May1st to 15thNight
18%7%35%5%3335%7%36%
1576
16th to endNight
18%5%244345%5%8%38%
1495
June1st to 15thNight
20%5%234245%5%8%38%
1440
16th to endNight
9%5%25%4245%5%8%45%
1440
July1st to 15thNight
12%6%245%346%5%7%41%
1440
16th to endNight
10%5%36%425%6%6%8%40%
1514
August1st to 15thNight
11%5%24425%46%7%44%
1606
16th to endNight
14%4245%2445%8%43%
1910
September1st to 15thNight
15%415%32435%5%48%
1800
16th to endNight
13%424313336%52%
1977
October1st to 15thNight
17%6%25%413335%45%
2097
16th to endNight
18%6%25%424345%41%
2415
November1st to 15thNight
15%7%34323446%44%
2472
16th to endNight
16%6%25%42435%6%41%
2594
December1st to 15thNight
20%7%35%42445%6%35%
2730
16th to endNight
20%8%2442445%6%35%
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
41%412%24%12%4
1553
16th to endDay
42%313%24%13%1
1736
February1st to 15thDay
48%311%21%12%1
1776
16th to endDay
45%311%25%13%1
1710
March1st to 15thDay
48%214%22%10%1
1950
16th to endDay
45%39%20%17%3
2291
April1st to 15thDay
46%310%21%14%3
2152
16th to endDay
41%48%23%19%2
2193
May1st to 15thDay
49%5%8%20%13%2
2385
16th to endDay
45%7%13%19%12%1
2622
June1st to 15thDay
47%6%13%21%10%1
2520
16th to endDay
42%7%12%24%11%
2520
July1st to 15thDay
42%6%11%21%15%1
2371
16th to endDay
41%6%14%22%13%2
2487
August1st to 15thDay
41%6%14%22%15%
2325
16th to endDay
38%5%10%27%17%
2292
September1st to 15thDay
40%5%9%22%19%1
2160
16th to endDay
37%5%7%25%22%2
1983
October1st to 15thDay
44%49%22%16%2
1860
16th to endDay
44%311%25%14%1
1809
November1st to 15thDay
41%313%22%16%2
1716
16th to endDay
40%310%28%14%1
1693
December1st to 15thDay
48%316%18%12%1
1560
16th to endDay
49%314%20%10%
1664
January1st to 15thNight
41%313%23%13%3
2716
16th to endNight
43%212%24%14%2
2837
February1st to 15thNight
46%414%20%12%2
2416
16th to endNight
43%210%23%17%2
2049
March1st to 15thNight
45%313%21%12%2
2340
16th to endNight
42%210%22%18%3
2058
April1st to 15thNight
47%310%21%14%2
1796
16th to endNight
43%48%21%19%2
1767
May1st to 15thNight
46%410%20%15%2
1576
16th to endNight
42%6%17%18%13%1
1497
June1st to 15thNight
43%6%14%20%12%1
1440
16th to endNight
34%6%15%28%13%1
1440
July1st to 15thNight
40%6%13%24%14%2
1360
16th to endNight
38%6%15%23%13%2
1418
August1st to 15thNight
35%6%14%27%15%1
1596
16th to endNight
38%6%11%23%19%1
1910
September1st to 15thNight
36%5%11%27%18%1
1800
16th to endNight
33%48%23%28%1
1977
October1st to 15thNight
41%410%24%17%2
2097
16th to endNight
43%312%25%14%
2415
November1st to 15thNight
41%411%22%17%3
2472
16th to endNight
43%311%26%13%2
2594
December1st to 15thNight
48%413%21%11%
2730
16th to endNight
47%413%22%12%
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
21%34%25%14%4
90
16th to endDay
21%22%37%18%
113
February1st to 15thDay
27%28%29%15%
199
16th to endDay
25%22%30%18%2
291
March1st to 15thDay
27%20%32%16%3
330
16th to endDay
22%22%34%12%5%2
311
April1st to 15thDay
27%16%29%18%7%
270
16th to endDay
23%14%31%16%11%2
270
May1st to 15thDay
36%12%23%16%6%3
288
16th to endDay
21%9%26%26%13%1
331
June1st to 15thDay
25%9%26%23%13%1
315
16th to endDay
16%11%30%23%15%2
315
July1st to 15thDay
16%7%29%29%13%3
305
16th to endDay
15%5%21%33%20%3
326
August1st to 15thDay
17%5%19%32%18%6%
313
16th to endDay
14%420%28%21%11%
332
September1st to 15thDay
14%12%25%23%13%10%
315
16th to endDay
15%6%25%21%14%15%
314
October1st to 15thDay
23%6%21%27%16%4
315
16th to endDay
21%14%28%24%11%
308
November1st to 15thDay
22%11%28%23%11%2
280
16th to endDay
23%21%25%21%5%1
223
December1st to 15thDay
23%27%27%11%10%
90
16th to endDay
28%32%32%7%
96
January1st to 15thNight
20%19%33%22%3
780
16th to endNight
21%18%34%23%1
832
February1st to 15thNight
21%17%40%19%1
764
16th to endNight
22%20%35%19%2
683
March1st to 15thNight
25%21%32%18%2
780
16th to endNight
21%21%30%20%5%
792
April1st to 15thNight
23%17%34%20%3
718
16th to endNight
21%14%35%21%5%
687
May1st to 15thNight
23%13%34%23%6%
496
16th to endNight
21%6%26%33%10%1
375
June1st to 15thNight
21%6%26%33%11%
360
16th to endNight
11%229%42%13%
360
July1st to 15thNight
18%222%38%16%
340
16th to endNight
11%223%38%22%1
376
August1st to 15thNight
15%121%40%19%1
525
16th to endNight
16%315%35%25%2
764
September1st to 15thNight
17%5%25%34%14%2
720
16th to endNight
16%5%23%28%22%4
717
October1st to 15thNight
19%9%26%27%15%1
720
16th to endNight
24%11%32%23%7%
768
November1st to 15thNight
20%13%30%25%9%1
760
16th to endNight
20%17%29%22%9%
780
December1st to 15thNight
26%13%30%22%6%
780
16th to endNight
25%17%36%18%2
832
Page generated at 2018-03-22 11:34:24. Version ac04

Copyright 2018 A. Danko


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