UConn at Avery Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the UConn at Avery Point clear sky chart from 2005-11-06 to 2026-03-03.

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	17% 7% 2 5% 4 4 4 3 5% 7% 41%	130516
	Night	18% 8% 2 6% 4 4 4 3 5% 6% 41%	130617
Transparency	Day	28% 37% 7% 15% 10% 2	134062
	Night	29% 36% 7% 14% 12% 2	135158
Seeing	Day	21% 12% 31% 24% 10% 2	16723
	Night	22% 11% 29% 27% 10% 1	25819

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	12% 8% 2 5% 3 4 4 4 6% 6% 46%	4661
	11th to 20th	Day	16% 8% 2 5% 4 3 3 3 4 5% 47%	4650
	21st to end	Day	16% 8% 2 5% 3 3 3 2 4 6% 47%	5142
February	1st to 10th	Day	17% 6% 2 5% 4 5% 5% 4 6% 7% 38%	2029
	11th to 20th	Day	14% 8% 2 6% 4 4 5% 4 6% 6% 42%	2048
	21st to end	Day	20% 8% 3 6% 3 3 3 3 5% 7% 39%	1730
March	1st to 10th	Day	21% 8% 2 5% 3 3 3 2 4 6% 42%	4496
	11th to 20th	Day	14% 10% 2 5% 3 3 4 3 5% 7% 43%	4699
	21st to end	Day	22% 8% 2 5% 4 4 4 3 5% 7% 36%	5878
April	1st to 10th	Day	20% 7% 2 4 4 4 4 4 5% 6% 41%	2400
	11th to 20th	Day	19% 7% 2 6% 3 3 4 3 5% 6% 43%	2374
	21st to end	Day	20% 6% 2 5% 4 4 4 4 6% 7% 40%	2551
May	1st to 10th	Day	28% 10% 3 6% 3 3 4 3 5% 8% 27%	5886
	11th to 20th	Day	21% 8% 3 7% 4 4 4 3 5% 5% 36%	5952
	21st to end	Day	20% 8% 2 6% 4 4 4 3 6% 7% 35%	6949
June	1st to 10th	Day	18% 6% 2 5% 4 4 5% 5% 7% 9% 37%	2800
	11th to 20th	Day	15% 7% 2 5% 4 4 5% 4 5% 8% 41%	2800
	21st to end	Day	13% 6% 2 5% 3 3 5% 4 7% 9% 41%	2800
July	1st to 10th	Day	18% 9% 2 7% 5% 3 4 3 6% 9% 34%	6360
	11th to 20th	Day	15% 7% 2 6% 5% 4 5% 4 6% 9% 35%	6360
	21st to end	Day	17% 6% 2 5% 4 4 4 4 5% 7% 44%	6926
August	1st to 10th	Day	17% 6% 3 7% 5% 4 4 4 5% 8% 36%	4285
	11th to 20th	Day	13% 5% 2 6% 4 4 4 4 6% 8% 45%	3958
	21st to end	Day	7% 4 2 6% 4 4 5% 4 7% 8% 49%	4312
September	1st to 10th	Day	14% 6% 3 5% 5% 3 4 4 5% 6% 46%	2400
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 7% 53%	2222
	21st to end	Day	19% 6% 3 6% 3 4 4 4 5% 6% 41%	2200
October	1st to 10th	Day	20% 5% 2 5% 4 3 4 3 4 6% 44%	2200
	11th to 20th	Day	15% 5% 2 5% 2 3 4 3 5% 8% 48%	1972
	21st to end	Day	18% 5% 2 5% 4 3 3 4 5% 6% 44%	1980
November	1st to 10th	Day	13% 6% 2 5% 4 3 4 3 4 5% 49%	1851
	11th to 20th	Day	16% 6% 1 4 4 3 3 3 5% 6% 49%	1890
	21st to end	Day	18% 6% 2 5% 4 3 3 3 5% 6% 45%	1890
December	1st to 10th	Day	15% 6% 2 6% 3 3 4 3 5% 7% 46%	2751
	11th to 20th	Day	21% 7% 3 4 3 2 2 2 4 6% 47%	3066
	21st to end	Day	21% 10% 3 6% 4 3 3 2 3 5% 40%	4048
January	1st to 10th	Night	16% 7% 3 5% 3 3 3 2 4 7% 48%	8234
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 3 5% 44%	8235
	21st to end	Night	16% 8% 2 6% 5% 4 5% 3 5% 6% 40%	9022
February	1st to 10th	Night	16% 9% 3 6% 5% 3 3 4 4 6% 41%	2589
	11th to 20th	Night	19% 7% 2 5% 4 3 3 3 5% 7% 42%	2458
	21st to end	Night	19% 9% 2 5% 5% 4 4 2 5% 5% 39%	2076
March	1st to 10th	Night	22% 8% 2 5% 3 3 3 3 5% 5% 41%	5389
	11th to 20th	Night	17% 10% 3 6% 3 4 4 3 5% 6% 40%	5260
	21st to end	Night	22% 9% 2 6% 3 4 4 4 5% 5% 36%	5038
April	1st to 10th	Night	20% 9% 2 5% 4 3 4 3 5% 6% 37%	2000
	11th to 20th	Night	20% 7% 2 5% 4 4 4 3 4 5% 42%	1975
	21st to end	Night	21% 8% 2 6% 4 3 4 3 4 5% 40%	1847
May	1st to 10th	Night	28% 11% 4 6% 4 4 3 3 4 6% 27%	4054
	11th to 20th	Night	24% 10% 3 6% 4 4 4 3 5% 7% 30%	3970
	21st to end	Night	23% 9% 3 6% 4 4 4 3 6% 7% 31%	3926
June	1st to 10th	Night	19% 7% 3 5% 4 4 4 4 6% 7% 38%	1600
	11th to 20th	Night	20% 8% 2 4 3 3 4 4 5% 10% 38%	1600
	21st to end	Night	15% 7% 2 6% 4 4 4 4 6% 9% 40%	1600
July	1st to 10th	Night	22% 10% 3 7% 4 3 4 4 5% 7% 31%	3600
	11th to 20th	Night	20% 11% 3 7% 4 4 5% 4 6% 8% 31%	3600
	21st to end	Night	15% 7% 3 6% 5% 4 4 3 5% 6% 42%	3926
August	1st to 10th	Night	23% 7% 2 7% 5% 5% 5% 4 6% 8% 29%	2817
	11th to 20th	Night	10% 6% 2 7% 5% 5% 6% 5% 6% 9% 39%	3085
	21st to end	Night	8% 4 1 4 3 3 4 3 6% 8% 54%	3586
September	1st to 10th	Night	14% 7% 2 6% 4 5% 5% 5% 6% 6% 41%	2000
	11th to 20th	Night	13% 7% 2 4 3 3 2 3 4 6% 52%	2177
	21st to end	Night	18% 8% 3 6% 5% 4 4 4 5% 5% 38%	2200
October	1st to 10th	Night	18% 7% 3 6% 4 3 3 3 4 6% 43%	2200
	11th to 20th	Night	15% 6% 2 6% 3 3 3 3 5% 7% 47%	2421
	21st to end	Night	20% 7% 2 5% 4 3 4 3 5% 6% 41%	2860
November	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 47%	2667
	11th to 20th	Night	17% 7% 2 5% 2 3 3 3 4 5% 47%	2730
	21st to end	Night	15% 6% 2 6% 4 3 3 3 4 6% 46%	2730
December	1st to 10th	Night	17% 7% 2 5% 3 3 3 2 4 5% 48%	4647
	11th to 20th	Night	26% 6% 2 4 3 3 3 3 4 4 42%	5348
	21st to end	Night	20% 8% 3 6% 3 3 3 2 4 5% 43%	7150

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	32% 21% 6% 20% 18% 2	4662
	11th to 20th	Day	31% 22% 7% 18% 14% 8%	4680
	21st to end	Day	33% 23% 8% 20% 16% 1	5142
February	1st to 10th	Day	19% 59% 7% 8% 6% 1	2029
	11th to 20th	Day	20% 58% 2 10% 9% 1	2057
	21st to end	Day	18% 59% 6% 9% 6% 2	1730
March	1st to 10th	Day	34% 30% 7% 10% 9% 10%	4499
	11th to 20th	Day	27% 31% 10% 22% 9% 1	4699
	21st to end	Day	37% 29% 6% 10% 13% 5%	5878
April	1st to 10th	Day	20% 62% 5% 7% 6% 2	2400
	11th to 20th	Day	16% 62% 3 8% 10% 1	2374
	21st to end	Day	17% 62% 3 10% 6% 1	2551
May	1st to 10th	Day	43% 32% 13% 8% 4	5897
	11th to 20th	Day	38% 30% 11% 12% 8%	5956
	21st to end	Day	38% 31% 6% 16% 9%	6949
June	1st to 10th	Day	17% 62% 4 11% 7%	2800
	11th to 20th	Day	16% 61% 5% 10% 6% 1	2800
	21st to end	Day	14% 61% 4 11% 8% 1	2800
July	1st to 10th	Day	38% 29% 8% 15% 9% 1	6290
	11th to 20th	Day	35% 28% 12% 18% 7%	6285
	21st to end	Day	32% 26% 8% 20% 13% 1	6728
August	1st to 10th	Day	34% 37% 10% 14% 5%	4271
	11th to 20th	Day	24% 38% 11% 22% 5%	3997
	21st to end	Day	17% 38% 12% 20% 12% 1	4312
September	1st to 10th	Day	17% 57% 5% 13% 8%	2400
	11th to 20th	Day	16% 57% 4 10% 12% 1	2222
	21st to end	Day	22% 57% 4 9% 7%	2200
October	1st to 10th	Day	21% 36% 6% 17% 15% 5%	3590
	11th to 20th	Day	15% 36% 5% 15% 27% 3	3188
	21st to end	Day	18% 36% 10% 20% 15% 2	3180
November	1st to 10th	Day	19% 53% 7% 9% 10% 1	1851
	11th to 20th	Day	16% 54% 3 11% 13% 3	1890
	21st to end	Day	18% 53% 5% 15% 7% 2	1890
December	1st to 10th	Day	24% 35% 9% 22% 10%	2751
	11th to 20th	Day	28% 30% 9% 12% 16% 4	3066
	21st to end	Day	38% 26% 3 16% 13% 4	4048
January	1st to 10th	Night	31% 20% 8% 23% 16% 3	8234
	11th to 20th	Night	36% 21% 7% 16% 15% 5%	8280
	21st to end	Night	39% 22% 6% 15% 15% 3	9022
February	1st to 10th	Night	19% 59% 5% 10% 5% 1	2589
	11th to 20th	Night	18% 57% 3 10% 10% 2	2460
	21st to end	Night	20% 59% 4 9% 7% 2	2076
March	1st to 10th	Night	36% 29% 7% 11% 10% 7%	5399
	11th to 20th	Night	32% 30% 11% 16% 8% 2	5261
	21st to end	Night	38% 30% 3 7% 19% 4	5038
April	1st to 10th	Night	20% 62% 3 8% 5% 2	2000
	11th to 20th	Night	16% 62% 6% 7% 8% 1	1975
	21st to end	Night	19% 61% 3 8% 7% 1	1847
May	1st to 10th	Night	45% 30% 11% 8% 5%	4060
	11th to 20th	Night	42% 32% 9% 10% 4 2	3971
	21st to end	Night	40% 30% 8% 15% 6%	3927
June	1st to 10th	Night	17% 62% 3 10% 9% 1	1600
	11th to 20th	Night	16% 62% 5% 11% 6% 1	1600
	21st to end	Night	14% 61% 5% 12% 7% 1	1600
July	1st to 10th	Night	43% 27% 6% 14% 8% 1	3560
	11th to 20th	Night	42% 28% 10% 15% 6%	3552
	21st to end	Night	32% 27% 9% 19% 12%	3809
August	1st to 10th	Night	39% 38% 7% 10% 5% 1	2807
	11th to 20th	Night	26% 39% 10% 20% 4	3112
	21st to end	Night	13% 37% 12% 22% 15% 1	3586
September	1st to 10th	Night	17% 58% 4 14% 7% 1	2000
	11th to 20th	Night	16% 57% 4 10% 12% 1	2177
	21st to end	Night	24% 58% 3 7% 8% 1	2200
October	1st to 10th	Night	23% 37% 7% 17% 13% 2	3590
	11th to 20th	Night	12% 35% 5% 16% 28% 4	3944
	21st to end	Night	18% 36% 7% 20% 18% 1	4610
November	1st to 10th	Night	19% 54% 5% 10% 10% 2	2667
	11th to 20th	Night	17% 54% 4 9% 13% 4	2730
	21st to end	Night	18% 54% 6% 15% 7% 2	2730
December	1st to 10th	Night	27% 34% 7% 21% 11% 1	4647
	11th to 20th	Night	34% 31% 6% 11% 16% 2	5348
	21st to end	Night	34% 27% 6% 14% 16% 3	7150

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	25% 26% 29% 15% 5%	220
	11th to 20th	Day	28% 25% 33% 12% 2	220
	21st to end	Day	23% 21% 38% 12% 6%	245
February	1st to 10th	Day	24% 19% 36% 17% 3	469
	11th to 20th	Day	24% 23% 38% 13% 1	536
	21st to end	Day	26% 19% 37% 14% 3	446
March	1st to 10th	Day	24% 20% 34% 19% 3	508
	11th to 20th	Day	19% 20% 39% 17% 4 1	500
	21st to end	Day	27% 17% 35% 15% 6%	550
April	1st to 10th	Day	25% 20% 32% 16% 6% 1	500
	11th to 20th	Day	25% 13% 37% 18% 6% 1	492
	21st to end	Day	28% 12% 33% 20% 5% 3	500
May	1st to 10th	Day	29% 13% 32% 19% 5% 1	503
	11th to 20th	Day	22% 9% 36% 25% 6% 2	527
	21st to end	Day	22% 6% 26% 31% 13% 3	573
June	1st to 10th	Day	18% 8% 29% 25% 16% 3	530
	11th to 20th	Day	20% 6% 30% 32% 9% 3	530
	21st to end	Day	18% 6% 28% 29% 15% 3	530
July	1st to 10th	Day	20% 4 24% 31% 17% 4	525
	11th to 20th	Day	15% 4 22% 38% 15% 6%	524
	21st to end	Day	15% 5% 30% 36% 12% 3	576
August	1st to 10th	Day	13% 6% 28% 35% 14% 5%	526
	11th to 20th	Day	16% 3 23% 36% 17% 5%	519
	21st to end	Day	12% 4 29% 31% 17% 6%	583
September	1st to 10th	Day	20% 5% 26% 28% 15% 6%	530
	11th to 20th	Day	16% 4 28% 28% 15% 7%	530
	21st to end	Day	24% 6% 29% 28% 11% 2	530
October	1st to 10th	Day	26% 8% 26% 22% 14% 5%	530
	11th to 20th	Day	18% 15% 29% 24% 13% 1	497
	21st to end	Day	25% 12% 30% 23% 8% 2	462
November	1st to 10th	Day	17% 12% 34% 24% 11% 2	425
	11th to 20th	Day	21% 20% 34% 19% 7%	430
	21st to end	Day	22% 20% 29% 20% 7% 1	430
December	1st to 10th	Day	22% 21% 37% 14% 6%	265
	11th to 20th	Day	27% 22% 31% 15% 4	220
	21st to end	Day	29% 16% 34% 14% 5% 3	242
January	1st to 10th	Night	21% 20% 35% 21% 3	840
	11th to 20th	Night	29% 18% 33% 18% 3	840
	21st to end	Night	23% 20% 34% 20% 2	924
February	1st to 10th	Night	22% 17% 36% 24% 2	840
	11th to 20th	Night	25% 15% 40% 17% 2	823
	21st to end	Night	26% 16% 37% 18% 3	692
March	1st to 10th	Night	24% 15% 34% 22% 4	809
	11th to 20th	Night	21% 12% 36% 25% 6% 1	800
	21st to end	Night	23% 12% 36% 22% 6% 1	880
April	1st to 10th	Night	27% 9% 32% 26% 5%	800
	11th to 20th	Night	24% 8% 32% 27% 8%	791
	21st to end	Night	25% 6% 31% 28% 9% 1	647
May	1st to 10th	Night	28% 6% 25% 30% 10% 2	600
	11th to 20th	Night	23% 5% 34% 30% 7% 1	568
	21st to end	Night	24% 3 18% 34% 17% 3	433
June	1st to 10th	Night	22% 4 21% 33% 20% 1	400
	11th to 20th	Night	25% 4 17% 38% 16% 1	400
	21st to end	Night	19% 3 17% 40% 21% 1	400
July	1st to 10th	Night	20% 3 16% 34% 25% 3	390
	11th to 20th	Night	15% 3 13% 42% 25% 2	388
	21st to end	Night	17% 3 14% 45% 20% 1	438
August	1st to 10th	Night	13% 3 15% 43% 23% 2	538
	11th to 20th	Night	15% 2 16% 38% 24% 4	714
	21st to end	Night	15% 2 14% 39% 25% 6%	880
September	1st to 10th	Night	18% 2 22% 35% 19% 4	800
	11th to 20th	Night	17% 4 21% 31% 22% 6%	800
	21st to end	Night	23% 5% 24% 29% 16% 3	800
October	1st to 10th	Night	23% 7% 25% 26% 14% 5%	800
	11th to 20th	Night	19% 11% 32% 26% 11% 2	800
	21st to end	Night	24% 11% 35% 21% 8% 1	880
November	1st to 10th	Night	16% 12% 32% 27% 12% 2	820
	11th to 20th	Night	23% 18% 32% 21% 6% 1	840
	21st to end	Night	18% 20% 32% 23% 7% 1	840
December	1st to 10th	Night	25% 18% 31% 20% 4 1	840
	11th to 20th	Night	27% 18% 33% 18% 4	840
	21st to end	Night	26% 15% 35% 20% 4	924

Page generated at 2026-02-28 01:40:24. Version ac07

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