Port Chester
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Chester clear sky chart from 2005-11-05 to 2018-10-27.

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
33%
16417
19%
51232
9%
16386
44%
16386
22%
32859

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
38%
776
19%
1664
January16th to endNight
18%
832
21%
2834
6%
832
37%
832
19%
1753
February1st to 15thNight
17%
764
17%
2401
3%
761
33%
761
18%
1593
February16th to endNight
20%
683
25%
2049
9%
683
41%
683
21%
1319
March1st to 15thNight
21%
780
18%
2340
7%
780
36%
780
20%
1549
March16th to endNight
24%
832
24%
2158
9%
832
36%
832
25%
1444
April1st to 15thNight
26%
778
18%
1946
5%
778
32%
778
24%
1354
April16th to endNight
29%
735
18%
1891
5%
735
36%
735
26%
1290
May1st to 15thNight
29%
559
17%
1729
6%
559
38%
559
20%
1172
May16th to endNight
42%
406
14%
1625
13%
406
49%
406
17%
1048
June1st to 15thNight
41%
390
15%
1560
13%
390
52%
390
17%
992
June16th to endNight
58%
390
14%
1560
16%
390
64%
390
26%
892
July1st to 15thNight
55%
370
13%
1480
17%
370
58%
370
21%
897
July16th to endNight
59%
408
16%
1546
17%
386
64%
386
24%
902
August1st to 15thNight
54%
577
18%
1718
12%
575
57%
575
30%
1079
August16th to endNight
59%
828
17%
2070
9%
828
62%
828
33%
1360
September1st to 15thNight
47%
780
22%
1953
11%
780
51%
780
31%
1302
September16th to endNight
51%
777
24%
2145
17%
777
56%
777
31%
1363
October1st to 15thNight
38%
780
19%
2262
13%
780
46%
780
24%
1485
October16th to endNight
28%
816
21%
2562
10%
816
42%
816
24%
1597
November1st to 15thNight
31%
760
21%
2472
11%
760
46%
760
23%
1535
November16th to endNight
27%
780
23%
2573
11%
780
42%
780
21%
1586
December1st to 15thNight
23%
780
15%
2730
6%
780
35%
780
16%
1788
December16th to endNight
16%
832
19%
2912
5%
832
34%
832
16%
1895

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%5%2442445%7%40%
52329
Night
17%5%24424446%42%
51402
Cloud CoverDay
15%5%2442445%7%42%
52338
Night
16%6%24424446%42%
51408
TransparencyDay
40%6%12%22%15%2
52017
Night
41%5%12%22%15%2
51232
SeeingDay
19%10%28%25%12%3
7230
Night
19%11%30%27%10%1
16418

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
16%5%145%24446%42%
1552
16th to endDay
15%7%25%42335%7%41%
1742
February1st to 15thDay
16%6%26%5%34346%40%
1790
16th to endDay
17%6%243345%46%41%
1710
March1st to 15thDay
17%6%245%3446%7%37%
1940
16th to endDay
18%6%25%423345%42%
2414
April1st to 15thDay
19%7%34423346%39%
2332
16th to endDay
16%5%2442435%5%44%
2342
May1st to 15thDay
21%6%3442445%7%35%
2562
16th to endDay
19%5%2442445%8%37%
2842
June1st to 15thDay
20%5%25%42435%8%35%
2730
16th to endDay
11%5%25%5%25%5%6%9%39%
2730
July1st to 15thDay
11%6%25%4345%6%9%40%
2730
16th to endDay
12%5%25%5%35%5%7%8%38%
2878
August1st to 15thDay
12%5%15%6%345%7%8%40%
2469
16th to endDay
12%4244345%5%8%44%
2484
September1st to 15thDay
14%5%245%2445%7%44%
2337
16th to endDay
15%5%15%43335%5%45%
2145
October1st to 15thDay
19%6%24433446%41%
2025
16th to endDay
17%425%324445%45%
1919
November1st to 15thDay
19%6%23223447%43%
1716
16th to endDay
16%424323446%46%
1716
December1st to 15thDay
17%6%35%42335%6%39%
1560
16th to endDay
21%7%2442335%5%38%
1664
January1st to 15thNight
18%424413446%44%
2716
16th to endNight
15%8%33323346%43%
2834
February1st to 15thNight
16%7%36%424346%40%
2400
16th to endNight
19%5%24423345%43%
2049
March1st to 15thNight
19%6%24324447%40%
2327
16th to endNight
16%6%24324345%45%
2158
April1st to 15thNight
18%7%25%42445%6%39%
1946
16th to endNight
20%5%35%412336%42%
1891
May1st to 15thNight
20%6%245%33446%37%
1729
16th to endNight
20%6%25%5%24347%38%
1623
June1st to 15thNight
21%5%24424447%39%
1560
16th to endNight
10%42442445%9%45%
1560
July1st to 15thNight
12%425%5%36%46%8%40%
1560
16th to endNight
11%424435%5%6%9%40%
1642
August1st to 15thNight
11%4245%345%5%8%45%
1728
16th to endNight
13%3145%245%5%8%44%
2070
September1st to 15thNight
16%413424445%46%
1953
16th to endNight
14%6%35%333235%49%
2145
October1st to 15thNight
18%6%25%423335%44%
2262
16th to endNight
18%5%24423346%44%
2562
November1st to 15thNight
17%6%24323445%46%
2472
16th to endNight
18%42442345%6%43%
2573
December1st to 15thNight
19%6%25%434446%37%
2730
16th to endNight
19%6%2442435%6%39%
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%24424448%42%
1552
16th to endDay
15%7%3442345%7%41%
1742
February1st to 15thDay
16%6%26%5%24347%40%
1790
16th to endDay
16%434435%446%43%
1710
March1st to 15thDay
17%6%2442445%8%38%
1950
16th to endDay
17%6%34423336%43%
2413
April1st to 15thDay
17%7%34423447%40%
2332
16th to endDay
16%423424346%45%
2342
May1st to 15thDay
19%7%25%32345%7%37%
2562
16th to endDay
17%5%2343445%9%39%
2842
June1st to 15thDay
18%5%34424448%39%
2730
16th to endDay
10%5%25%5%25%5%5%9%42%
2730
July1st to 15thDay
9%425%435%5%6%8%43%
2730
16th to endDay
11%5%25%5%35%5%6%9%40%
2878
August1st to 15thDay
11%424425%5%6%9%42%
2469
16th to endDay
11%42442445%9%47%
2484
September1st to 15thDay
13%424434446%46%
2337
16th to endDay
14%6%14424346%46%
2145
October1st to 15thDay
17%7%34333446%41%
2025
16th to endDay
17%325%433446%45%
1919
November1st to 15thDay
18%6%23323446%44%
1716
16th to endDay
14%6%23425%446%46%
1716
December1st to 15thDay
16%6%35%42345%6%39%
1560
16th to endDay
21%8%2342335%6%37%
1664
January1st to 15thNight
17%5%24324445%44%
2716
16th to endNight
16%9%33323447%42%
2834
February1st to 15thNight
15%8%35%5%34436%39%
2393
16th to endNight
18%6%24424345%43%
2049
March1st to 15thNight
19%6%2342445%6%40%
2340
16th to endNight
17%6%23423346%44%
2158
April1st to 15thNight
18%6%25%33445%6%39%
1946
16th to endNight
19%5%25%423336%42%
1891
May1st to 15thNight
18%6%26%434446%37%
1729
16th to endNight
19%6%2443445%6%38%
1623
June1st to 15thNight
19%6%3441345%6%39%
1560
16th to endNight
9%5%24435%46%9%44%
1560
July1st to 15thNight
10%426%435%5%7%8%40%
1560
16th to endNight
9%5%335%35%5%6%10%40%
1642
August1st to 15thNight
9%4245%35%46%7%45%
1728
16th to endNight
12%424435%45%8%44%
2070
September1st to 15thNight
15%414424446%45%
1953
16th to endNight
13%6%25%5%23345%48%
2145
October1st to 15thNight
16%7%345%23335%43%
2262
16th to endNight
18%5%24333345%45%
2562
November1st to 15thNight
16%6%24424345%46%
2472
16th to endNight
16%5%25%423446%43%
2573
December1st to 15thNight
19%6%3443445%6%37%
2730
16th to endNight
18%6%35%42445%6%38%
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%413%23%13%3
1553
16th to endDay
42%413%24%13%2
1742
February1st to 15thDay
44%5%12%21%13%2
1793
16th to endDay
41%5%11%26%14%1
1710
March1st to 15thDay
43%5%15%22%10%1
1950
16th to endDay
43%410%20%17%3
2414
April1st to 15thDay
44%410%21%15%3
2332
16th to endDay
39%5%10%21%20%3
2342
May1st to 15thDay
45%6%11%19%15%1
2562
16th to endDay
42%7%15%20%12%1
2846
June1st to 15thDay
44%7%13%21%12%
2730
16th to endDay
37%8%14%23%14%1
2730
July1st to 15thDay
36%10%11%22%17%1
2581
16th to endDay
38%8%15%21%12%3
2711
August1st to 15thDay
37%7%16%22%15%
2455
16th to endDay
33%7%13%24%19%1
2484
September1st to 15thDay
37%5%14%21%19%1
2337
16th to endDay
39%5%10%21%22%2
2145
October1st to 15thDay
43%5%11%21%16%1
2025
16th to endDay
39%410%24%18%1
1919
November1st to 15thDay
41%412%19%18%2
1716
16th to endDay
39%212%26%15%2
1716
December1st to 15thDay
43%5%15%18%14%1
1560
16th to endDay
46%5%14%20%12%
1664
January1st to 15thNight
41%412%23%14%3
2716
16th to endNight
41%411%24%15%2
2834
February1st to 15thNight
45%5%12%21%12%2
2401
16th to endNight
42%38%24%17%3
2049
March1st to 15thNight
44%412%21%13%3
2340
16th to endNight
41%49%21%18%4
2158
April1st to 15thNight
44%411%20%15%2
1946
16th to endNight
43%49%18%21%3
1891
May1st to 15thNight
47%412%17%15%2
1729
16th to endNight
44%7%14%18%13%1
1625
June1st to 15thNight
44%6%11%20%15%1
1560
16th to endNight
35%6%15%26%14%1
1560
July1st to 15thNight
38%9%14%20%16%1
1480
16th to endNight
35%8%16%24%12%3
1546
August1st to 15thNight
35%8%13%24%15%1
1718
16th to endNight
36%7%14%22%18%
2070
September1st to 15thNight
39%5%11%26%16%1
1953
16th to endNight
39%38%22%24%2
2145
October1st to 15thNight
43%411%23%15%2
2262
16th to endNight
40%412%24%16%
2562
November1st to 15thNight
40%410%21%18%3
2472
16th to endNight
41%410%27%14%2
2573
December1st to 15thNight
46%5%14%19%13%
2730
16th to endNight
45%5%12%21%13%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%33%27%16%5%
90
16th to endDay
21%10%45%18%4
114
February1st to 15thDay
23%18%39%17%
216
16th to endDay
21%18%35%20%4
291
March1st to 15thDay
19%20%36%19%4
330
16th to endDay
20%14%38%20%32
352
April1st to 15thDay
22%14%36%15%9%1
330
16th to endDay
22%9%35%20%10%2
319
May1st to 15thDay
29%11%28%21%7%1
348
16th to endDay
24%6%23%28%15%2
395
June1st to 15thDay
21%8%25%28%14%1
375
16th to endDay
14%428%34%15%2
375
July1st to 15thDay
12%322%35%19%6%
365
16th to endDay
14%321%31%23%5%
390
August1st to 15thDay
14%221%33%20%7%
358
16th to endDay
11%217%37%19%11%
396
September1st to 15thDay
17%5%29%22%17%8%
375
16th to endDay
20%423%24%16%11%
374
October1st to 15thDay
25%6%20%27%15%4
375
16th to endDay
16%16%32%24%10%
350
November1st to 15thDay
23%11%28%23%10%1
280
16th to endDay
17%20%30%21%8%1
246
December1st to 15thDay
17%25%35%12%7%1
90
16th to endDay
32%22%37%7%
96
January1st to 15thNight
20%17%36%21%3
780
16th to endNight
20%17%40%19%1
832
February1st to 15thNight
20%15%41%21%1
764
16th to endNight
21%19%34%22%2
683
March1st to 15thNight
23%15%37%20%3
780
16th to endNight
20%14%36%22%5%
832
April1st to 15thNight
20%14%36%23%5%
778
16th to endNight
22%10%33%25%7%
735
May1st to 15thNight
21%10%32%27%7%
559
16th to endNight
22%423%37%10%
407
June1st to 15thNight
23%324%36%12%
390
16th to endNight
10%221%51%14%
390
July1st to 15thNight
12%219%44%19%1
370
16th to endNight
11%317%43%21%1
408
August1st to 15thNight
12%121%41%21%1
577
16th to endNight
13%316%34%28%3
828
September1st to 15thNight
18%324%33%17%3
780
16th to endNight
18%420%30%21%5%
777
October1st to 15thNight
20%7%27%27%14%1
780
16th to endNight
21%13%34%22%7%
816
November1st to 15thNight
19%12%30%24%11%1
760
16th to endNight
20%15%30%24%7%
780
December1st to 15thNight
24%15%33%19%6%
780
16th to endNight
24%16%40%17%2
832
Page generated at 2018-10-28 08:41:04. Version ac04

Copyright 2018 A. Danko


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