Bridgeport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bridgeport clear sky chart from 2005-11-06 to 2024-11-05.

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% 6% 2 5% 4 4 4 4 6% 7% 40%	101266
	Night	19% 7% 2 5% 4 4 4 3 5% 6% 41%	97784
Transparency	Day	40% 7% 13% 23% 16% 2	104812
	Night	42% 6% 12% 22% 16% 2	102327
Seeing	Day	18% 6% 24% 30% 17% 4	15034
	Night	20% 8% 30% 29% 12% 1	24088

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	16% 6% 2 5% 3 3 3 3 5% 5% 46%	2517
	11th to 20th	Day	17% 9% 3 6% 5% 4 4 4 5% 5% 37%	2520
	21st to end	Day	23% 9% 3 7% 4 4 4 4 5% 6% 33%	2902
February	1st to 10th	Day	18% 7% 2 5% 5% 4 4 4 5% 7% 39%	1763
	11th to 20th	Day	15% 6% 2 4 5% 3 4 3 5% 7% 44%	1848
	21st to end	Day	21% 8% 2 5% 4 4 4 3 5% 6% 38%	1570
March	1st to 10th	Day	28% 9% 2 5% 3 3 3 3 4 5% 35%	3116
	11th to 20th	Day	10% 5% 1 5% 4 5% 5% 4 8% 8% 46%	3272
	21st to end	Day	21% 7% 2 6% 3 3 3 3 5% 5% 41%	4166
April	1st to 10th	Day	20% 8% 2 6% 4 3 4 4 6% 7% 38%	2280
	11th to 20th	Day	18% 6% 3 5% 4 4 4 3 5% 6% 41%	2254
	21st to end	Day	21% 6% 2 5% 4 4 4 3 5% 6% 41%	2361
May	1st to 10th	Day	29% 9% 2 4 3 3 3 3 5% 7% 31%	4106
	11th to 20th	Day	23% 7% 2 6% 4 4 4 3 5% 6% 35%	4288
	21st to end	Day	16% 4 2 4 4 3 4 4 6% 8% 45%	4837
June	1st to 10th	Day	19% 5% 2 5% 4 4 4 4 7% 8% 38%	2660
	11th to 20th	Day	16% 6% 2 4 4 4 4 4 7% 9% 39%	2660
	21st to end	Day	15% 5% 2 5% 5% 4 4 4 6% 9% 40%	2660
July	1st to 10th	Day	12% 6% 2 7% 5% 5% 5% 5% 7% 9% 37%	4440
	11th to 20th	Day	14% 6% 2 5% 4 4 4 5% 7% 9% 40%	4440
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 4 6% 8% 34%	4814
August	1st to 10th	Day	19% 6% 2 6% 4 5% 5% 4 6% 8% 34%	4228
	11th to 20th	Day	13% 6% 2 6% 4 3 4 4 6% 8% 45%	3730
	21st to end	Day	9% 4 2 5% 4 4 5% 4 7% 8% 48%	4180
September	1st to 10th	Day	14% 5% 2 6% 4 4 5% 3 4 7% 46%	2280
	11th to 20th	Day	13% 5% 2 4 3 4 4 3 4 6% 52%	2161
	21st to end	Day	20% 6% 2 6% 4 4 3 3 5% 6% 41%	2090
October	1st to 10th	Day	22% 6% 2 4 2 3 3 3 5% 7% 42%	2043
	11th to 20th	Day	16% 4 2 4 4 3 4 3 5% 7% 48%	1900
	21st to end	Day	21% 5% 1 5% 4 3 4 3 5% 7% 42%	1887
November	1st to 10th	Day	14% 6% 2 4 3 4 4 2 5% 5% 50%	1708
	11th to 20th	Day	19% 5% 2 4 3 3 3 3 5% 5% 48%	1710
	21st to end	Day	17% 6% 2 5% 4 3 3 3 5% 7% 45%	1677
December	1st to 10th	Day	19% 6% 2 6% 4 4 5% 4 6% 7% 37%	1520
	11th to 20th	Day	24% 5% 2 4 2 3 3 3 4 7% 44%	1906
	21st to end	Day	20% 11% 3 6% 5% 4 4 3 5% 6% 33%	2772
January	1st to 10th	Night	18% 7% 2 4 3 3 3 3 4 6% 47%	4429
	11th to 20th	Night	18% 9% 3 5% 3 3 3 3 4 5% 44%	4440
	21st to end	Night	25% 11% 3 6% 4 3 3 3 3 5% 34%	4752
February	1st to 10th	Night	17% 9% 3 6% 4 3 4 3 5% 5% 41%	2414
	11th to 20th	Night	17% 8% 3 5% 4 3 3 2 4 7% 42%	2218
	21st to end	Night	20% 8% 2 5% 4 3 4 3 4 4 42%	1884
March	1st to 10th	Night	26% 11% 2 5% 3 3 3 2 4 5% 35%	3724
	11th to 20th	Night	13% 6% 2 6% 5% 5% 3 3 5% 7% 46%	3685
	21st to end	Night	21% 9% 3 5% 3 3 3 3 5% 4 42%	3466
April	1st to 10th	Night	19% 8% 2 6% 4 3 4 4 4 6% 39%	1900
	11th to 20th	Night	20% 7% 2 5% 4 3 4 3 4 6% 42%	1875
	21st to end	Night	20% 6% 2 6% 4 3 3 4 5% 4 43%	1819
May	1st to 10th	Night	26% 10% 3 7% 4 4 4 2 4 7% 29%	2834
	11th to 20th	Night	24% 9% 3 6% 4 4 4 3 5% 6% 31%	2633
	21st to end	Night	20% 6% 2 5% 3 3 4 3 5% 7% 43%	2738
June	1st to 10th	Night	19% 5% 2 5% 5% 4 4 3 5% 6% 41%	1520
	11th to 20th	Night	16% 7% 2 5% 3 4 4 3 6% 9% 41%	1520
	21st to end	Night	13% 6% 1 6% 5% 4 4 3 7% 9% 42%	1520
July	1st to 10th	Night	13% 7% 3 7% 5% 5% 5% 5% 6% 8% 36%	2520
	11th to 20th	Night	17% 6% 2 6% 4 4 4 4 7% 9% 36%	2520
	21st to end	Night	20% 8% 2 6% 4 4 5% 4 6% 7% 33%	2739
August	1st to 10th	Night	24% 6% 2 7% 4 4 5% 5% 6% 6% 31%	2655
	11th to 20th	Night	16% 6% 2 6% 4 5% 5% 4 5% 7% 39%	3097
	21st to end	Night	9% 4 2 4 3 4 4 3 5% 7% 55%	3476
September	1st to 10th	Night	15% 6% 2 6% 4 4 4 4 4 5% 46%	1900
	11th to 20th	Night	15% 5% 2 4 3 3 3 2 5% 7% 51%	2019
	21st to end	Night	19% 7% 3 4 3 4 4 3 4 5% 44%	2090
October	1st to 10th	Night	20% 7% 2 6% 4 4 4 2 5% 6% 41%	2134
	11th to 20th	Night	15% 5% 2 5% 3 4 3 2 4 7% 50%	2280
	21st to end	Night	22% 7% 2 5% 3 3 3 3 4 6% 42%	2710
November	1st to 10th	Night	13% 6% 2 5% 4 4 3 3 5% 6% 50%	2470
	11th to 20th	Night	20% 7% 2 4 3 3 3 2 4 6% 47%	2470
	21st to end	Night	15% 6% 2 5% 4 3 4 2 5% 6% 47%	2501
December	1st to 10th	Night	21% 7% 2 5% 4 4 4 3 5% 6% 40%	2660
	11th to 20th	Night	21% 6% 2 5% 3 3 3 3 5% 6% 43%	3288
	21st to end	Night	22% 9% 3 5% 3 3 3 2 4 5% 38%	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	39% 5% 11% 31% 12% 2	2518
	11th to 20th	Day	44% 6% 14% 24% 11% 1	2520
	21st to end	Day	50% 8% 10% 20% 10% 2	2902
February	1st to 10th	Day	44% 4 14% 22% 14% 2	1763
	11th to 20th	Day	39% 6% 10% 25% 17% 3	1857
	21st to end	Day	46% 5% 11% 21% 14% 3	1570
March	1st to 10th	Day	50% 5% 12% 21% 10% 2	3119
	11th to 20th	Day	29% 8% 17% 32% 14% 1	3272
	21st to end	Day	43% 5% 8% 18% 21% 5%	4166
April	1st to 10th	Day	42% 7% 11% 21% 15% 4	2280
	11th to 20th	Day	41% 5% 12% 21% 18% 3	2254
	21st to end	Day	42% 5% 11% 22% 17% 4	2361
May	1st to 10th	Day	49% 7% 16% 15% 12% 1	4120
	11th to 20th	Day	46% 7% 16% 19% 9% 2	4292
	21st to end	Day	33% 8% 13% 25% 19% 2	4837
June	1st to 10th	Day	39% 8% 14% 23% 14% 1	2660
	11th to 20th	Day	37% 8% 16% 24% 13% 1	2660
	21st to end	Day	36% 8% 16% 24% 15% 1	2660
July	1st to 10th	Day	40% 10% 13% 20% 16% 1	4370
	11th to 20th	Day	37% 7% 18% 23% 13% 1	4365
	21st to end	Day	46% 7% 13% 17% 15% 1	4661
August	1st to 10th	Day	45% 7% 17% 22% 8%	4214
	11th to 20th	Day	35% 6% 16% 31% 12% 1	3766
	21st to end	Day	30% 8% 13% 30% 18% 2	4180
September	1st to 10th	Day	36% 8% 13% 22% 19% 2	2280
	11th to 20th	Day	31% 6% 12% 25% 25% 2	2161
	21st to end	Day	42% 6% 11% 20% 18% 3	2090
October	1st to 10th	Day	34% 6% 11% 21% 23% 5%	3394
	11th to 20th	Day	27% 4 11% 24% 31% 4	3140
	21st to end	Day	30% 4 15% 25% 22% 3	3087
November	1st to 10th	Day	36% 6% 13% 23% 20% 2	1708
	11th to 20th	Day	39% 4 11% 22% 21% 3	1710
	21st to end	Day	38% 5% 14% 27% 13% 3	1677
December	1st to 10th	Day	45% 6% 15% 19% 14% 1	1520
	11th to 20th	Day	41% 3 16% 21% 17% 2	1906
	21st to end	Day	50% 7% 11% 22% 9% 1	2772
January	1st to 10th	Night	39% 6% 12% 29% 12% 3	4429
	11th to 20th	Night	44% 5% 13% 24% 13% 2	4440
	21st to end	Night	53% 5% 9% 21% 11% 2	4752
February	1st to 10th	Night	45% 6% 12% 23% 13% 2	2414
	11th to 20th	Night	44% 4 10% 20% 17% 5%	2220
	21st to end	Night	44% 4 8% 23% 16% 4	1884
March	1st to 10th	Night	52% 4 10% 20% 11% 2	3734
	11th to 20th	Night	37% 7% 14% 24% 15% 3	3686
	21st to end	Night	45% 5% 7% 13% 23% 6%	3466
April	1st to 10th	Night	45% 6% 11% 19% 16% 3	1900
	11th to 20th	Night	44% 5% 10% 19% 21% 1	1875
	21st to end	Night	44% 5% 9% 21% 16% 5%	1819
May	1st to 10th	Night	54% 7% 13% 15% 10% 1	2840
	11th to 20th	Night	53% 7% 14% 14% 10% 1	2634
	21st to end	Night	41% 7% 13% 23% 14% 2	2739
June	1st to 10th	Night	44% 5% 11% 20% 18% 2	1520
	11th to 20th	Night	39% 7% 15% 26% 12% 1	1520
	21st to end	Night	37% 9% 14% 26% 14% 1	1520
July	1st to 10th	Night	45% 8% 15% 18% 13% 1	2480
	11th to 20th	Night	42% 8% 16% 23% 10% 1	2472
	21st to end	Night	48% 7% 15% 14% 14% 2	2651
August	1st to 10th	Night	50% 9% 15% 16% 9% 1	2645
	11th to 20th	Night	42% 7% 13% 28% 9% 1	3127
	21st to end	Night	28% 7% 13% 32% 20% 1	3476
September	1st to 10th	Night	39% 6% 9% 26% 18% 2	1900
	11th to 20th	Night	34% 6% 10% 23% 24% 3	2019
	21st to end	Night	43% 6% 8% 20% 20% 3	2090
October	1st to 10th	Night	39% 6% 11% 23% 19% 3	3563
	11th to 20th	Night	25% 4 10% 27% 31% 4	3779
	21st to end	Night	32% 5% 13% 27% 21% 2	4460
November	1st to 10th	Night	36% 6% 12% 22% 20% 4	2470
	11th to 20th	Night	40% 5% 9% 24% 19% 4	2470
	21st to end	Night	38% 5% 13% 30% 13% 2	2501
December	1st to 10th	Night	45% 5% 13% 21% 15% 1	2660
	11th to 20th	Night	44% 4 13% 18% 18% 3	3288
	21st to end	Night	48% 5% 12% 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	19% 15% 33% 24% 8% 1	180
	11th to 20th	Day	16% 17% 46% 16% 5% 1	180
	21st to end	Day	21% 6% 39% 25% 8% 1	236
February	1st to 10th	Day	23% 9% 40% 24% 5%	323
	11th to 20th	Day	18% 11% 43% 25% 2	456
	21st to end	Day	23% 13% 35% 22% 6% 1	382
March	1st to 10th	Day	17% 9% 37% 30% 6%	460
	11th to 20th	Day	14% 8% 42% 28% 7% 1	460
	21st to end	Day	22% 9% 35% 26% 7% 1	506
April	1st to 10th	Day	23% 9% 33% 24% 10% 1	460
	11th to 20th	Day	19% 7% 31% 30% 12% 1	452
	21st to end	Day	25% 6% 25% 33% 10% 1	460
May	1st to 10th	Day	27% 5% 25% 32% 10% 2	463
	11th to 20th	Day	19% 4 23% 34% 18% 1	487
	21st to end	Day	17% 2 15% 33% 27% 6%	529
June	1st to 10th	Day	18% 3 15% 36% 23% 5%	490
	11th to 20th	Day	16% 2 17% 37% 23% 4	490
	21st to end	Day	14% 3 17% 36% 26% 5%	490
July	1st to 10th	Day	13% 2 13% 31% 32% 9%	485
	11th to 20th	Day	11% 2 9% 34% 35% 8%	484
	21st to end	Day	13% 4 13% 37% 29% 3	532
August	1st to 10th	Day	12% 3 10% 38% 28% 9%	486
	11th to 20th	Day	15% 1 9% 35% 31% 9%	479
	21st to end	Day	11% 2 14% 37% 27% 10%	539
September	1st to 10th	Day	17% 2 16% 29% 25% 11%	490
	11th to 20th	Day	14% 3 17% 28% 27% 11%	490
	21st to end	Day	23% 3 20% 31% 19% 5%	490
October	1st to 10th	Day	24% 5% 18% 26% 20% 7%	490
	11th to 20th	Day	16% 7% 27% 30% 17% 3	490
	21st to end	Day	23% 9% 26% 28% 12% 2	432
November	1st to 10th	Day	15% 9% 24% 32% 16% 4	378
	11th to 20th	Day	20% 11% 36% 25% 8%	370
	21st to end	Day	18% 12% 31% 29% 10%	337
December	1st to 10th	Day	17% 13% 37% 24% 8% 1	180
	11th to 20th	Day	27% 14% 31% 24% 4	180
	21st to end	Day	23% 9% 38% 22% 8% 1	198
January	1st to 10th	Night	19% 15% 40% 21% 5%	760
	11th to 20th	Night	24% 14% 36% 23% 3	760
	21st to end	Night	20% 13% 40% 25% 2	836
February	1st to 10th	Night	20% 11% 39% 27% 2	760
	11th to 20th	Night	22% 11% 44% 21% 2	743
	21st to end	Night	23% 12% 38% 22% 5%	628
March	1st to 10th	Night	22% 9% 38% 26% 5%	760
	11th to 20th	Night	19% 9% 39% 26% 6% 1	760
	21st to end	Night	22% 8% 38% 26% 6%	836
April	1st to 10th	Night	21% 8% 34% 30% 6% 1	760
	11th to 20th	Night	23% 5% 31% 32% 9%	751
	21st to end	Night	21% 5% 33% 33% 8% 1	679
May	1st to 10th	Night	26% 6% 26% 30% 11% 1	570
	11th to 20th	Night	22% 3 31% 32% 11%	460
	21st to end	Night	21% 3 14% 36% 24% 2	411
June	1st to 10th	Night	19% 3 23% 35% 18% 2	380
	11th to 20th	Night	18% 2 16% 43% 21% 1	380
	21st to end	Night	14% 1 16% 48% 20% 1	380
July	1st to 10th	Night	14% 1 17% 38% 28% 2	370
	11th to 20th	Night	13% 2 12% 43% 27% 3	368
	21st to end	Night	16% 2 15% 45% 22% 1	416
August	1st to 10th	Night	11% 1 16% 44% 26% 2	462
	11th to 20th	Night	15% 3 13% 36% 29% 4	750
	21st to end	Night	14% 2 17% 34% 29% 4	836
September	1st to 10th	Night	17% 2 22% 33% 22% 4	760
	11th to 20th	Night	17% 3 18% 34% 22% 6%	760
	21st to end	Night	21% 3 23% 32% 18% 3	760
October	1st to 10th	Night	23% 7% 27% 23% 16% 4	760
	11th to 20th	Night	17% 9% 30% 32% 11% 1	760
	21st to end	Night	25% 9% 33% 25% 8% 1	836
November	1st to 10th	Night	16% 8% 34% 28% 12% 2	760
	11th to 20th	Night	23% 12% 34% 24% 8% 1	760
	21st to end	Night	18% 14% 34% 27% 7% 1	760
December	1st to 10th	Night	24% 13% 34% 22% 6% 1	760
	11th to 20th	Night	23% 13% 36% 25% 4	760
	21st to end	Night	24% 12% 37% 23% 3	836

Page generated at 2024-11-03 02:11:18. Version ac07

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