Woonsocket
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woonsocket clear sky chart from 2005-11-05 to 2018-11-30.

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
25%
16473
18%
51650
7%
16441
37%
16441
19%
33997

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
14%
780
19%
2716
5%
776
31%
776
15%
1738
January16th to endNight
13%
832
19%
2912
3%
832
33%
832
14%
1908
February1st to 15thNight
14%
764
17%
2358
4%
761
30%
761
16%
1608
February16th to endNight
14%
683
22%
2049
5%
683
33%
683
17%
1368
March1st to 15thNight
16%
780
16%
2340
5%
780
30%
780
16%
1619
March16th to endNight
18%
832
22%
2194
6%
832
32%
832
20%
1494
April1st to 15thNight
18%
778
17%
1946
4%
778
27%
778
19%
1398
April16th to endNight
21%
642
17%
1798
4%
642
30%
642
20%
1235
May1st to 15thNight
21%
585
14%
1755
6%
585
29%
585
16%
1224
May16th to endNight
23%
457
10%
1675
6%
456
30%
456
15%
1133
June1st to 15thNight
27%
390
12%
1560
7%
390
39%
390
15%
1042
June16th to endNight
35%
390
12%
1560
12%
390
44%
390
21%
952
July1st to 15thNight
40%
370
13%
1480
13%
370
49%
370
22%
882
July16th to endNight
44%
408
14%
1546
13%
386
50%
386
19%
964
August1st to 15thNight
41%
541
16%
1682
10%
539
46%
539
26%
1068
August16th to endNight
50%
800
20%
2042
11%
800
53%
800
34%
1323
September1st to 15thNight
38%
780
18%
2015
8%
780
44%
780
28%
1366
September16th to endNight
43%
777
23%
2145
16%
777
49%
777
29%
1380
October1st to 15thNight
33%
780
22%
2171
10%
780
45%
780
25%
1422
October16th to endNight
23%
832
18%
2701
6%
832
37%
832
21%
1727
November1st to 15thNight
25%
820
20%
2667
9%
820
40%
820
20%
1739
November16th to endNight
22%
840
21%
2728
8%
840
38%
840
19%
1713
December1st to 15thNight
18%
780
17%
2698
5%
780
33%
780
15%
1775
December16th to endNight
13%
832
19%
2912
4%
832
32%
832
15%
1919

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%6%25%42445%7%39%
52657
Night
16%7%25%424446%41%
51820
Cloud CoverDay
17%6%2442445%6%39%
52667
Night
16%7%25%424446%41%
51825
TransparencyDay
44%6%11%20%14%2
52345
Night
43%5%11%20%15%2
51650
SeeingDay
22%15%31%19%8%2
7422
Night
21%14%34%22%6%
16473

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%7%3442335%6%42%
1552
16th to endDay
15%6%345%23446%43%
1664
February1st to 15thDay
17%7%25%5%35%5%6%6%35%
1828
16th to endDay
16%8%35%434446%40%
1710
March1st to 15thDay
20%7%34424447%35%
1940
16th to endDay
17%7%35%424346%42%
2379
April1st to 15thDay
19%7%25%43435%6%36%
2332
16th to endDay
19%414424447%41%
2435
May1st to 15thDay
24%7%25%414346%33%
2527
16th to endDay
17%6%25%42435%7%39%
2802
June1st to 15thDay
23%6%245%2435%7%32%
2730
16th to endDay
14%5%25%5%35%6%6%9%35%
2730
July1st to 15thDay
13%4246%45%5%5%8%38%
2730
16th to endDay
13%5%25%6%35%5%6%8%37%
2878
August1st to 15thDay
13%5%16%5%35%5%6%8%37%
2505
16th to endDay
11%5%25%5%35%5%5%8%42%
2510
September1st to 15thDay
15%5%24424445%45%
2275
16th to endDay
17%5%14323335%48%
2145
October1st to 15thDay
21%6%24423335%42%
2119
16th to endDay
16%5%24333446%44%
1875
November1st to 15thDay
21%6%24423245%41%
1851
16th to endDay
17%5%2432346%6%43%
1887
December1st to 15thDay
17%7%343235%47%40%
1589
16th to endDay
21%8%34325%346%36%
1664
January1st to 15thNight
17%7%35%5%23345%41%
2716
16th to endNight
16%9%34423345%40%
2912
February1st to 15thNight
16%8%35%5%335%45%38%
2357
16th to endNight
17%8%34434335%41%
2049
March1st to 15thNight
17%8%345%3445%5%37%
2327
16th to endNight
16%8%35%423335%42%
2194
April1st to 15thNight
16%8%36%44445%6%36%
1946
16th to endNight
21%6%24423325%41%
1798
May1st to 15thNight
21%6%35%42345%6%35%
1755
16th to endNight
17%6%26%5%34446%35%
1673
June1st to 15thNight
20%6%24335%45%7%35%
1560
16th to endNight
14%5%3443445%8%41%
1560
July1st to 15thNight
12%5%25%43446%8%41%
1560
16th to endNight
12%5%25%5%46%5%6%8%39%
1642
August1st to 15thNight
9%425%5%246%6%8%43%
1692
16th to endNight
11%4143245%5%8%47%
2042
September1st to 15thNight
15%5%15%4445%5%6%42%
2015
16th to endNight
14%5%24423335%48%
2145
October1st to 15thNight
19%5%2431335%5%45%
2171
16th to endNight
17%5%25%434345%42%
2701
November1st to 15thNight
17%6%245%34235%43%
2667
16th to endNight
18%6%24323345%43%
2728
December1st to 15thNight
18%8%245%23445%39%
2698
16th to endNight
17%9%35%32345%5%38%
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%34323446%43%
1552
16th to endDay
15%6%34423446%43%
1664
February1st to 15thDay
18%7%25%435%45%6%36%
1828
16th to endDay
16%9%34425%346%40%
1710
March1st to 15thDay
21%8%2442445%7%35%
1950
16th to endDay
16%8%25%423436%41%
2379
April1st to 15thDay
19%7%35%5%23446%37%
2332
16th to endDay
19%424424446%42%
2435
May1st to 15thDay
24%7%35%423346%33%
2527
16th to endDay
17%6%25%43435%7%39%
2802
June1st to 15thDay
23%7%25%42445%7%32%
2730
16th to endDay
14%5%35%5%35%5%6%10%35%
2730
July1st to 15thDay
12%425%6%45%5%6%8%37%
2730
16th to endDay
13%435%5%35%6%7%8%35%
2878
August1st to 15thDay
13%5%25%5%45%5%6%7%37%
2505
16th to endDay
11%5%25%5%35%5%6%7%42%
2510
September1st to 15thDay
15%5%25%4335%45%44%
2275
16th to endDay
17%5%14323435%47%
2145
October1st to 15thDay
21%6%25%323336%42%
2119
16th to endDay
15%5%25%424345%45%
1875
November1st to 15thDay
21%7%23423345%42%
1851
16th to endDay
17%5%2442345%6%43%
1887
December1st to 15thDay
18%6%24424445%41%
1589
16th to endDay
21%7%2442435%6%36%
1664
January1st to 15thNight
17%8%25%5%23245%42%
2716
16th to endNight
16%10%35%423345%40%
2912
February1st to 15thNight
16%7%35%5%245%46%38%
2350
16th to endNight
16%9%34424335%41%
2049
March1st to 15thNight
18%8%345%2445%6%36%
2340
16th to endNight
15%8%35%433335%42%
2193
April1st to 15thNight
16%7%35%44445%6%37%
1946
16th to endNight
21%6%25%422435%40%
1798
May1st to 15thNight
21%6%35%5%24447%35%
1755
16th to endNight
18%6%35%5%2445%6%35%
1673
June1st to 15thNight
20%6%35%5%2445%6%36%
1560
16th to endNight
15%5%3442445%8%41%
1560
July1st to 15thNight
11%5%25%425%5%5%9%41%
1560
16th to endNight
12%435%5%36%5%6%8%38%
1642
August1st to 15thNight
8%5%26%5%25%5%7%8%42%
1692
16th to endNight
11%5%1432445%7%47%
2042
September1st to 15thNight
15%5%15%5%35%5%46%42%
2015
16th to endNight
15%5%25%413435%47%
2145
October1st to 15thNight
18%6%24323446%44%
2171
16th to endNight
17%5%25%424446%42%
2701
November1st to 15thNight
18%6%25%324335%43%
2667
16th to endNight
18%6%24323346%43%
2728
December1st to 15thNight
18%7%35%423445%39%
2698
16th to endNight
17%9%35%41335%7%37%
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
42%6%10%23%13%3
1553
16th to endDay
41%5%10%26%14%1
1664
February1st to 15thDay
46%5%13%18%13%2
1831
16th to endDay
45%411%21%14%3
1710
March1st to 15thDay
47%5%12%21%9%2
1950
16th to endDay
44%49%19%15%5%
2379
April1st to 15thDay
48%411%18%15%2
2332
16th to endDay
42%5%9%20%18%4
2435
May1st to 15thDay
51%410%16%14%2
2527
16th to endDay
43%7%13%20%13%1
2806
June1st to 15thDay
50%6%11%19%10%1
2730
16th to endDay
43%7%13%19%14%
2730
July1st to 15thDay
42%7%11%21%14%2
2581
16th to endDay
42%8%15%18%11%3
2711
August1st to 15thDay
44%7%14%19%13%
2491
16th to endDay
38%7%11%23%17%1
2510
September1st to 15thDay
40%6%12%20%19%2
2275
16th to endDay
38%48%20%24%2
2145
October1st to 15thDay
44%49%22%14%3
2119
16th to endDay
39%5%11%22%16%2
1875
November1st to 15thDay
45%413%20%14%1
1851
16th to endDay
40%5%12%23%15%2
1887
December1st to 15thDay
44%5%14%17%16%
1589
16th to endDay
48%7%12%17%12%1
1664
January1st to 15thNight
45%411%21%14%2
2716
16th to endNight
46%410%19%15%2
2912
February1st to 15thNight
46%6%12%19%12%2
2358
16th to endNight
45%410%19%16%2
2049
March1st to 15thNight
47%5%11%19%12%2
2340
16th to endNight
44%49%17%19%4
2194
April1st to 15thNight
48%49%18%15%2
1946
16th to endNight
46%5%8%18%15%5%
1798
May1st to 15thNight
49%5%12%15%14%2
1755
16th to endNight
48%7%15%17%9%1
1675
June1st to 15thNight
47%8%13%17%12%1
1560
16th to endNight
39%8%12%24%14%1
1560
July1st to 15thNight
37%8%13%24%15%
1480
16th to endNight
40%8%14%23%9%2
1546
August1st to 15thNight
37%8%15%22%13%2
1682
16th to endNight
34%7%12%26%18%
2042
September1st to 15thNight
41%6%12%21%17%
2015
16th to endNight
39%5%7%21%25%1
2145
October1st to 15thNight
40%6%11%22%15%3
2171
16th to endNight
42%412%23%15%
2701
November1st to 15thNight
43%5%10%21%15%2
2667
16th to endNight
41%412%23%15%2
2728
December1st to 15thNight
46%5%13%20%12%
2698
16th to endNight
46%5%12%20%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
21%36%30%11%1
90
16th to endDay
26%23%40%9%
96
February1st to 15thDay
28%26%32%10%2
282
16th to endDay
21%29%31%14%2
291
March1st to 15thDay
30%18%34%12%3
330
16th to endDay
21%24%35%12%5%1
352
April1st to 15thDay
27%22%32%11%6%
330
16th to endDay
24%16%32%20%33
319
May1st to 15thDay
31%20%25%16%41
348
16th to endDay
22%11%39%20%6%
395
June1st to 15thDay
27%14%31%19%7%1
375
16th to endDay
16%15%36%23%6%2
375
July1st to 15thDay
16%6%35%26%13%1
365
16th to endDay
13%6%34%27%13%3
390
August1st to 15thDay
14%8%30%29%13%3
358
16th to endDay
12%6%32%27%14%7%
396
September1st to 15thDay
20%10%24%26%15%4
375
16th to endDay
23%7%29%17%11%10%
374
October1st to 15thDay
26%9%28%21%9%5%
375
16th to endDay
18%22%30%18%9%
337
November1st to 15thDay
28%14%30%16%8%2
325
16th to endDay
24%20%30%16%7%
329
December1st to 15thDay
23%31%27%10%6%
119
16th to endDay
29%34%30%5%1
96
January1st to 15thNight
21%20%39%14%3
780
16th to endNight
24%20%36%16%1
832
February1st to 15thNight
21%19%39%17%1
764
16th to endNight
24%20%35%16%2
683
March1st to 15thNight
23%22%35%16%2
780
16th to endNight
23%20%34%18%3
832
April1st to 15thNight
22%21%35%17%2
778
16th to endNight
23%17%35%18%5%
642
May1st to 15thNight
27%14%32%20%3
585
16th to endNight
21%9%39%24%4
457
June1st to 15thNight
21%6%36%29%5%
390
16th to endNight
15%338%35%6%
390
July1st to 15thNight
12%436%35%10%
370
16th to endNight
12%133%40%10%
408
August1st to 15thNight
11%434%39%9%
541
16th to endNight
15%226%39%15%1
800
September1st to 15thNight
18%432%31%12%
780
16th to endNight
19%7%24%29%17%2
777
October1st to 15thNight
23%8%30%24%12%1
780
16th to endNight
22%16%35%18%7%
832
November1st to 15thNight
21%15%32%19%10%
820
16th to endNight
22%19%30%19%6%
840
December1st to 15thNight
25%18%33%18%4
780
16th to endNight
25%20%36%15%1
832
Page generated at 2018-12-01 11:35:35. Version ac04

Copyright 2018 A. Danko


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