Woonsocket
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woonsocket clear sky chart from 2005-11-06 to 2024-11-08.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	18% 8% 2 6% 4 4 4 4 5% 7% 39%	101230
	Night	18% 8% 2 6% 4 4 4 3 5% 6% 39%	97882
Transparency	Day	43% 6% 12% 21% 15% 2	104781
	Night	43% 6% 12% 21% 15% 2	102407
Seeing	Day	23% 18% 32% 18% 7% 2	15089
	Night	22% 15% 34% 23% 6%	23999

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 9% 2 6% 4 4 2 3 5% 5% 46%	2517
	11th to 20th	Day	17% 9% 3 6% 4 4 4 3 5% 4 40%	2520
	21st to end	Day	22% 12% 3 7% 3 4 4 3 4 5% 34%	2772
February	1st to 10th	Day	19% 7% 2 5% 4 5% 5% 4 6% 6% 36%	1795
	11th to 20th	Day	14% 8% 3 6% 4 4 4 4 5% 6% 41%	1848
	21st to end	Day	19% 11% 3 6% 4 4 4 3 4 5% 37%	1570
March	1st to 10th	Day	24% 14% 3 7% 4 3 3 3 4 5% 31%	3116
	11th to 20th	Day	12% 6% 2 5% 5% 4 6% 4 5% 7% 44%	3319
	21st to end	Day	22% 10% 2 6% 4 3 4 3 5% 6% 36%	4052
April	1st to 10th	Day	19% 10% 3 6% 5% 3 4 3 5% 6% 38%	2280
	11th to 20th	Day	18% 6% 2 5% 4 4 4 3 6% 8% 39%	2254
	21st to end	Day	22% 6% 2 7% 4 3 5% 3 4 6% 37%	2466
May	1st to 10th	Day	26% 11% 3 7% 4 3 4 3 4 7% 28%	4106
	11th to 20th	Day	24% 9% 2 7% 4 4 3 3 4 6% 33%	4137
	21st to end	Day	16% 5% 2 5% 3 4 4 3 5% 8% 46%	4837
June	1st to 10th	Day	18% 6% 2 6% 5% 5% 5% 4 6% 8% 35%	2660
	11th to 20th	Day	17% 6% 2 6% 5% 5% 5% 4 6% 8% 37%	2660
	21st to end	Day	16% 7% 3 6% 6% 4 5% 4 6% 9% 36%	2660
July	1st to 10th	Day	14% 6% 3 6% 6% 6% 6% 5% 6% 8% 34%	4440
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 6% 10% 38%	4440
	21st to end	Day	19% 7% 3 6% 5% 4 5% 4 6% 7% 34%	4814
August	1st to 10th	Day	17% 7% 3 8% 5% 6% 5% 4 6% 8% 32%	4145
	11th to 20th	Day	14% 7% 3 6% 4 5% 5% 4 6% 7% 40%	3951
	21st to end	Day	7% 4 2 5% 5% 5% 5% 5% 7% 8% 46%	4180
September	1st to 10th	Day	15% 5% 2 5% 3 4 4 4 6% 5% 46%	2280
	11th to 20th	Day	15% 5% 2 4 4 3 4 2 4 6% 51%	2090
	21st to end	Day	19% 6% 2 5% 3 5% 3 3 4 6% 43%	2090
October	1st to 10th	Day	23% 7% 3 4 3 3 4 2 4 5% 42%	2090
	11th to 20th	Day	15% 6% 2 5% 3 3 4 3 4 7% 48%	1865
	21st to end	Day	20% 6% 3 5% 3 4 3 4 4 6% 42%	1881
November	1st to 10th	Day	16% 7% 2 5% 4 3 3 3 4 5% 48%	1734
	11th to 20th	Day	19% 7% 2 4 4 3 3 3 5% 6% 45%	1710
	21st to end	Day	17% 6% 2 5% 4 4 3 3 6% 6% 43%	1710
December	1st to 10th	Day	18% 9% 2 6% 4 4 5% 4 5% 6% 39%	1563
	11th to 20th	Day	20% 7% 2 4 4 3 3 2 3 5% 45%	1906
	21st to end	Day	21% 11% 3 7% 3 4 4 3 4 6% 34%	2772
January	1st to 10th	Night	17% 8% 2 4 3 3 3 2 4 6% 48%	4429
	11th to 20th	Night	16% 11% 4 8% 4 3 3 3 4 5% 40%	4440
	21st to end	Night	23% 12% 3 7% 4 4 4 3 4 5% 31%	4884
February	1st to 10th	Night	17% 9% 3 6% 5% 4 3 4 5% 6% 39%	2379
	11th to 20th	Night	15% 8% 3 6% 4 4 4 5% 5% 6% 40%	2218
	21st to end	Night	18% 9% 2 5% 4 4 4 2 4 6% 41%	1884
March	1st to 10th	Night	28% 11% 2 4 3 3 4 3 4 5% 33%	3724
	11th to 20th	Night	10% 10% 3 6% 5% 4 5% 4 5% 7% 42%	3639
	21st to end	Night	25% 9% 2 5% 4 3 4 3 5% 5% 34%	3576
April	1st to 10th	Night	18% 8% 3 7% 4 5% 5% 3 5% 6% 37%	1900
	11th to 20th	Night	19% 8% 2 6% 5% 4 4 4 5% 5% 38%	1875
	21st to end	Night	21% 8% 3 6% 4 3 3 3 3 6% 41%	1712
May	1st to 10th	Night	25% 9% 4 8% 3 4 4 4 5% 7% 28%	2834
	11th to 20th	Night	23% 9% 3 7% 6% 5% 5% 4 6% 6% 26%	2784
	21st to end	Night	16% 6% 2 6% 4 4 4 3 4 7% 42%	2738
June	1st to 10th	Night	16% 7% 3 6% 4 4 5% 4 5% 8% 38%	1520
	11th to 20th	Night	19% 8% 3 4 5% 4 5% 3 5% 8% 37%	1520
	21st to end	Night	15% 7% 2 6% 3 4 3 4 7% 9% 40%	1520
July	1st to 10th	Night	13% 7% 3 7% 5% 4 5% 5% 7% 10% 35%	2520
	11th to 20th	Night	14% 7% 2 6% 4 4 4 3 6% 9% 40%	2520
	21st to end	Night	18% 9% 3 7% 5% 5% 5% 4 6% 6% 33%	2739
August	1st to 10th	Night	20% 8% 3 7% 5% 4 5% 5% 6% 8% 29%	2752
	11th to 20th	Night	12% 7% 3 8% 6% 6% 6% 5% 6% 7% 35%	2872
	21st to end	Night	9% 4 2 4 3 3 3 3 5% 7% 56%	3476
September	1st to 10th	Night	13% 6% 2 7% 4 5% 4 4 5% 6% 44%	1900
	11th to 20th	Night	15% 6% 1 5% 3 3 3 2 4 6% 52%	2089
	21st to end	Night	18% 7% 3 7% 4 3 4 3 4 5% 42%	2090
October	1st to 10th	Night	21% 7% 2 5% 3 3 3 3 5% 5% 42%	2090
	11th to 20th	Night	15% 5% 2 5% 3 3 4 3 4 7% 48%	2311
	21st to end	Night	21% 7% 3 6% 4 4 4 2 4 5% 40%	2717
November	1st to 10th	Night	14% 6% 2 5% 4 4 3 3 5% 5% 49%	2505
	11th to 20th	Night	18% 8% 2 5% 4 3 4 3 4 5% 46%	2470
	21st to end	Night	16% 7% 2 4 4 3 4 3 5% 6% 45%	2470
December	1st to 10th	Night	19% 8% 3 6% 5% 4 3 3 4 5% 40%	2613
	11th to 20th	Night	19% 6% 2 5% 4 3 4 4 5% 6% 41%	3288
	21st to end	Night	20% 12% 3 7% 3 3 3 3 5% 6% 35%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 5% 9% 30% 14% 2	2518
	11th to 20th	Day	46% 7% 9% 24% 12% 2	2520
	21st to end	Day	51% 7% 8% 22% 10% 2	2772
February	1st to 10th	Day	46% 7% 13% 18% 14% 3	1795
	11th to 20th	Day	43% 6% 11% 21% 16% 3	1857
	21st to end	Day	49% 5% 11% 19% 14% 3	1570
March	1st to 10th	Day	55% 5% 12% 14% 11% 3	3119
	11th to 20th	Day	33% 10% 16% 26% 13% 3	3319
	21st to end	Day	49% 5% 8% 16% 16% 7%	4052
April	1st to 10th	Day	47% 5% 11% 19% 16% 3	2280
	11th to 20th	Day	42% 6% 11% 20% 18% 3	2254
	21st to end	Day	47% 6% 9% 18% 16% 4	2466
May	1st to 10th	Day	55% 8% 13% 13% 10% 1	4120
	11th to 20th	Day	51% 8% 14% 15% 10% 2	4141
	21st to end	Day	35% 9% 13% 23% 19% 2	4837
June	1st to 10th	Day	45% 8% 13% 21% 12% 1	2660
	11th to 20th	Day	43% 8% 13% 20% 14% 2	2660
	21st to end	Day	44% 7% 15% 20% 14% 1	2660
July	1st to 10th	Day	46% 7% 12% 20% 14% 2	4370
	11th to 20th	Day	42% 6% 17% 22% 12% 2	4365
	21st to end	Day	49% 6% 12% 19% 12% 2	4661
August	1st to 10th	Day	50% 7% 16% 19% 8%	4131
	11th to 20th	Day	43% 6% 14% 27% 10%	3990
	21st to end	Day	33% 6% 14% 27% 18% 1	4180
September	1st to 10th	Day	38% 7% 11% 22% 20% 2	2280
	11th to 20th	Day	35% 5% 10% 23% 24% 3	2090
	21st to end	Day	42% 5% 9% 19% 22% 2	2090
October	1st to 10th	Day	41% 4 9% 21% 21% 4	3480
	11th to 20th	Day	30% 4 7% 25% 29% 4	3068
	21st to end	Day	32% 4 13% 28% 20% 3	3081
November	1st to 10th	Day	39% 5% 13% 22% 18% 2	1734
	11th to 20th	Day	39% 5% 11% 22% 20% 3	1710
	21st to end	Day	41% 5% 13% 26% 12% 3	1710
December	1st to 10th	Day	45% 7% 13% 16% 17% 2	1563
	11th to 20th	Day	43% 5% 13% 17% 17% 5%	1906
	21st to end	Day	49% 8% 11% 20% 11% 1	2772
January	1st to 10th	Night	38% 4 12% 30% 12% 3	4429
	11th to 20th	Night	47% 6% 11% 22% 11% 3	4440
	21st to end	Night	56% 6% 9% 16% 11% 2	4884
February	1st to 10th	Night	45% 6% 13% 21% 13% 2	2379
	11th to 20th	Night	44% 6% 10% 19% 17% 4	2220
	21st to end	Night	45% 5% 9% 22% 15% 4	1884
March	1st to 10th	Night	52% 6% 9% 19% 11% 3	3734
	11th to 20th	Night	39% 8% 17% 18% 16% 3	3640
	21st to end	Night	51% 5% 7% 13% 17% 7%	3576
April	1st to 10th	Night	48% 6% 10% 19% 15% 3	1900
	11th to 20th	Night	46% 6% 9% 18% 18% 3	1875
	21st to end	Night	46% 6% 10% 19% 15% 4	1712
May	1st to 10th	Night	53% 10% 13% 14% 8% 2	2840
	11th to 20th	Night	54% 11% 14% 12% 7% 2	2785
	21st to end	Night	39% 10% 15% 21% 13% 1	2739
June	1st to 10th	Night	43% 9% 14% 20% 13% 1	1520
	11th to 20th	Night	44% 7% 13% 21% 13% 1	1520
	21st to end	Night	39% 9% 16% 23% 12% 1	1520
July	1st to 10th	Night	44% 9% 13% 21% 13% 1	2480
	11th to 20th	Night	42% 6% 18% 23% 11% 1	2472
	21st to end	Night	51% 7% 11% 16% 14% 2	2651
August	1st to 10th	Night	53% 7% 13% 17% 8% 1	2742
	11th to 20th	Night	46% 7% 14% 24% 9%	2899
	21st to end	Night	28% 5% 15% 29% 22% 1	3476
September	1st to 10th	Night	40% 7% 11% 22% 18% 2	1900
	11th to 20th	Night	34% 7% 9% 22% 26% 2	2089
	21st to end	Night	44% 6% 8% 20% 19% 2	2090
October	1st to 10th	Night	40% 5% 13% 23% 16% 3	3480
	11th to 20th	Night	26% 4 9% 27% 31% 3	3834
	21st to end	Night	34% 3 12% 29% 20% 3	4467
November	1st to 10th	Night	37% 7% 12% 23% 18% 3	2505
	11th to 20th	Night	42% 4 10% 22% 19% 3	2470
	21st to end	Night	39% 5% 13% 27% 14% 2	2470
December	1st to 10th	Night	46% 6% 12% 21% 14% 1	2613
	11th to 20th	Night	42% 6% 16% 18% 16% 2	3288
	21st to end	Night	48% 7% 10% 23% 11% 1	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	28% 27% 29% 14% 2	180
	11th to 20th	Day	29% 28% 32% 7% 4	180
	21st to end	Day	22% 31% 32% 11% 3 1	198
February	1st to 10th	Day	32% 24% 31% 11% 2	383
	11th to 20th	Day	28% 33% 29% 8% 1	456
	21st to end	Day	32% 23% 30% 12% 3	382
March	1st to 10th	Day	31% 20% 33% 13% 3	460
	11th to 20th	Day	28% 26% 31% 11% 3	460
	21st to end	Day	29% 23% 32% 10% 4 2	506
April	1st to 10th	Day	33% 23% 27% 12% 5% 1	460
	11th to 20th	Day	27% 25% 31% 13% 3 1	452
	21st to end	Day	28% 23% 30% 15% 2 2	460
May	1st to 10th	Day	31% 24% 28% 14% 3 1	463
	11th to 20th	Day	22% 17% 41% 14% 5%	487
	21st to end	Day	18% 16% 36% 23% 6% 2	529
June	1st to 10th	Day	21% 14% 35% 20% 8% 1	490
	11th to 20th	Day	17% 17% 38% 21% 6% 1	490
	21st to end	Day	17% 16% 37% 21% 7% 2	490
July	1st to 10th	Day	17% 9% 34% 25% 13% 1	485
	11th to 20th	Day	16% 7% 34% 27% 14% 2	484
	21st to end	Day	14% 9% 41% 27% 9% 1	532
August	1st to 10th	Day	12% 11% 34% 31% 10% 2	486
	11th to 20th	Day	15% 9% 34% 28% 12% 3	479
	21st to end	Day	11% 11% 34% 26% 13% 6%	539
September	1st to 10th	Day	18% 13% 27% 25% 14% 4	490
	11th to 20th	Day	19% 12% 27% 24% 11% 7%	490
	21st to end	Day	23% 12% 32% 21% 8% 3	490
October	1st to 10th	Day	28% 13% 26% 20% 9% 5%	490
	11th to 20th	Day	19% 17% 34% 17% 9% 3	442
	21st to end	Day	23% 18% 31% 18% 8% 1	429
November	1st to 10th	Day	20% 17% 34% 17% 9% 2	386
	11th to 20th	Day	28% 22% 28% 16% 5%	370
	21st to end	Day	25% 20% 32% 16% 6% 1	370
December	1st to 10th	Day	23% 32% 30% 11% 4	223
	11th to 20th	Day	31% 27% 33% 6% 2	180
	21st to end	Day	24% 29% 32% 9% 3 3	198
January	1st to 10th	Night	23% 20% 38% 16% 3	760
	11th to 20th	Night	28% 21% 35% 14% 2	760
	21st to end	Night	21% 23% 35% 18% 3	836
February	1st to 10th	Night	24% 19% 38% 18% 1	760
	11th to 20th	Night	24% 24% 37% 13% 1	743
	21st to end	Night	27% 21% 34% 15% 3	628
March	1st to 10th	Night	25% 20% 34% 17% 3	760
	11th to 20th	Night	20% 24% 36% 17% 3	760
	21st to end	Night	27% 20% 35% 15% 4	836
April	1st to 10th	Night	24% 22% 33% 18% 3	760
	11th to 20th	Night	23% 21% 35% 17% 4	751
	21st to end	Night	24% 19% 38% 16% 3	572
May	1st to 10th	Night	31% 15% 31% 20% 3	570
	11th to 20th	Night	23% 16% 38% 20% 3	546
	21st to end	Night	17% 9% 39% 29% 5%	411
June	1st to 10th	Night	18% 8% 37% 29% 8%	380
	11th to 20th	Night	19% 7% 37% 31% 5%	380
	21st to end	Night	16% 7% 39% 32% 6%	380
July	1st to 10th	Night	14% 5% 34% 38% 9%	370
	11th to 20th	Night	16% 4 31% 39% 10% 1	368
	21st to end	Night	13% 6% 34% 39% 7%	416
August	1st to 10th	Night	13% 5% 35% 38% 8%	520
	11th to 20th	Night	14% 6% 29% 39% 12%	613
	21st to end	Night	14% 6% 27% 38% 14% 2	836
September	1st to 10th	Night	16% 5% 34% 33% 11% 1	760
	11th to 20th	Night	18% 8% 28% 28% 16% 2	760
	21st to end	Night	23% 8% 29% 27% 11% 2	760
October	1st to 10th	Night	26% 10% 28% 24% 11% 2	760
	11th to 20th	Night	19% 12% 34% 23% 12% 1	760
	21st to end	Night	25% 16% 33% 19% 7%	836
November	1st to 10th	Night	16% 16% 34% 23% 9% 1	771
	11th to 20th	Night	24% 18% 35% 17% 6%	760
	21st to end	Night	22% 21% 32% 20% 4 1	760
December	1st to 10th	Night	26% 18% 34% 18% 4	760
	11th to 20th	Night	26% 19% 33% 20% 2	760
	21st to end	Night	26% 20% 35% 17% 2	836

Page generated at 2024-11-05 08:15:54. Version ac07

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