Middletown
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Middletown clear sky chart from 2005-11-06 to 2025-09-19.

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	15% 9% 3 8% 5% 4 4 4 5% 7% 36%	126328
	Night	15% 10% 3 8% 5% 4 4 3 5% 7% 36%	122803
Transparency	Day	47% 3 10% 24% 14% 2	129966
	Night	48% 3 10% 23% 14% 2	127234
Seeing	Day	19% 8% 25% 24% 16% 7%	16559
	Night	20% 7% 25% 32% 16% 2	26217

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 17% 8% 12% 4 4 3 3 3 5% 25%	3617
	11th to 20th	Day	14% 15% 6% 13% 6% 6% 4 3 3 4 25%	3901
	21st to end	Day	22% 14% 7% 9% 5% 5% 4 3 4 5% 23%	4466
February	1st to 10th	Day	19% 13% 5% 10% 5% 4 3 4 4 4 28%	1893
	11th to 20th	Day	18% 11% 4 12% 6% 4 3 3 4 5% 29%	1948
	21st to end	Day	19% 13% 4 10% 4 3 3 3 4 4 32%	1650
March	1st to 10th	Day	18% 14% 6% 9% 5% 4 3 3 4 4 30%	4521
	11th to 20th	Day	13% 9% 3 6% 4 4 4 3 6% 7% 41%	4980
	21st to end	Day	18% 10% 3 7% 5% 4 5% 4 5% 6% 33%	5465
April	1st to 10th	Day	16% 12% 3 7% 4 4 4 4 5% 7% 35%	2360
	11th to 20th	Day	17% 9% 3 6% 5% 4 4 3 4 7% 38%	2437
	21st to end	Day	17% 8% 3 8% 4 4 5% 4 5% 7% 35%	2600
May	1st to 10th	Day	21% 9% 3 8% 5% 5% 5% 4 5% 7% 29%	5862
	11th to 20th	Day	20% 8% 3 7% 4 4 4 3 5% 7% 35%	5861
	21st to end	Day	15% 6% 3 8% 5% 5% 5% 5% 7% 9% 33%	6433
June	1st to 10th	Day	13% 5% 2 6% 5% 5% 5% 4 6% 8% 40%	2620
	11th to 20th	Day	9% 6% 3 6% 6% 6% 5% 4 6% 9% 42%	2800
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 7% 10% 40%	2800
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 10% 40%	6360
	11th to 20th	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 10% 39%	6179
	21st to end	Day	11% 6% 3 8% 5% 6% 6% 5% 7% 9% 33%	6424
August	1st to 10th	Day	8% 5% 2 6% 4 5% 5% 4 7% 10% 43%	4234
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 5% 7% 10% 42%	4174
	21st to end	Day	6% 5% 2 5% 4 4 4 3 6% 8% 53%	4358
September	1st to 10th	Day	12% 5% 2 4 4 4 4 3 5% 7% 50%	2276
	11th to 20th	Day	9% 5% 2 5% 4 4 4 3 6% 8% 50%	2178
	21st to end	Day	16% 6% 2 6% 4 4 3 3 5% 6% 46%	2090
October	1st to 10th	Day	11% 5% 3 6% 4 4 5% 3 5% 6% 49%	2090
	11th to 20th	Day	15% 5% 2 7% 4 3 4 3 5% 7% 46%	1924
	21st to end	Day	21% 8% 2 6% 4 3 4 3 5% 6% 38%	1943
November	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 4 6% 52%	1762
	11th to 20th	Day	15% 11% 3 8% 5% 3 4 3 5% 6% 36%	1800
	21st to end	Day	19% 11% 4 8% 4 4 3 3 5% 5% 34%	1800
December	1st to 10th	Day	18% 11% 4 8% 4 4 4 2 3 4 37%	2930
	11th to 20th	Day	19% 15% 5% 9% 5% 5% 4 3 5% 5% 26%	3373
	21st to end	Day	23% 19% 5% 10% 5% 5% 4 3 4 5% 18%	4219
January	1st to 10th	Night	16% 16% 7% 14% 7% 5% 4 3 4 5% 19%	6348
	11th to 20th	Night	14% 18% 7% 13% 7% 5% 5% 3 4 5% 20%	6058
	21st to end	Night	22% 14% 5% 8% 5% 5% 4 3 3 5% 29%	6490
February	1st to 10th	Night	21% 12% 4 9% 5% 4 4 3 4 5% 29%	2505
	11th to 20th	Night	17% 11% 4 10% 6% 4 5% 3 4 6% 30%	2338
	21st to end	Night	21% 13% 4 8% 4 3 4 3 4 5% 31%	1980
March	1st to 10th	Night	21% 11% 3 6% 4 4 3 3 4 4 37%	5332
	11th to 20th	Night	12% 7% 2 6% 4 4 5% 4 6% 7% 43%	4980
	21st to end	Night	18% 9% 4 8% 4 4 4 3 5% 6% 35%	5467
April	1st to 10th	Night	16% 9% 3 6% 4 3 4 4 5% 7% 39%	2057
	11th to 20th	Night	15% 7% 2 6% 4 4 4 4 5% 7% 41%	1912
	21st to end	Night	17% 6% 3 6% 5% 4 4 4 6% 7% 38%	1800
May	1st to 10th	Night	22% 10% 3 7% 6% 5% 4 3 6% 6% 27%	4033
	11th to 20th	Night	17% 6% 2 6% 5% 5% 4 4 7% 9% 35%	4032
	21st to end	Night	14% 6% 3 6% 5% 5% 4 4 6% 8% 39%	4421
June	1st to 10th	Night	10% 5% 3 6% 4 4 4 2 5% 9% 48%	1774
	11th to 20th	Night	10% 5% 2 5% 4 4 5% 4 7% 10% 45%	1600
	21st to end	Night	6% 5% 2 5% 4 4 5% 5% 8% 10% 47%	1600
July	1st to 10th	Night	10% 5% 2 5% 5% 4 4 4 6% 9% 46%	3618
	11th to 20th	Night	9% 5% 2 7% 5% 4 5% 5% 7% 9% 44%	3787
	21st to end	Night	10% 6% 2 7% 5% 5% 5% 5% 7% 10% 40%	4427
August	1st to 10th	Night	9% 5% 2 7% 4 5% 5% 4 6% 8% 44%	2915
	11th to 20th	Night	7% 7% 2 7% 4 4 5% 4 6% 8% 47%	2875
	21st to end	Night	4 3 1 4 4 4 5% 4 7% 9% 57%	3536
September	1st to 10th	Night	12% 5% 2 5% 3 3 3 4 5% 7% 51%	2102
	11th to 20th	Night	9% 4 1 4 3 3 4 3 5% 7% 56%	2179
	21st to end	Night	15% 6% 2 6% 3 3 4 3 4 6% 49%	2090
October	1st to 10th	Night	9% 4 2 5% 4 4 3 3 5% 7% 55%	2090
	11th to 20th	Night	15% 7% 3 7% 4 4 4 2 5% 6% 45%	2255
	21st to end	Night	18% 8% 2 6% 4 4 4 3 5% 6% 40%	2651
November	1st to 10th	Night	13% 8% 2 5% 4 4 4 3 5% 6% 47%	2536
	11th to 20th	Night	17% 8% 3 6% 4 4 4 3 5% 6% 39%	2600
	21st to end	Night	20% 12% 5% 7% 5% 4 3 3 5% 7% 30%	2600
December	1st to 10th	Night	18% 11% 4 8% 4 4 3 3 4 5% 37%	4250
	11th to 20th	Night	20% 14% 6% 9% 5% 4 4 3 5% 5% 26%	4822
	21st to end	Night	24% 18% 6% 10% 6% 4 4 3 4 5% 17%	6743

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	64% 2 7% 19% 8%	3618
	11th to 20th	Day	65% 1 8% 13% 11% 1	3901
	21st to end	Day	65% 2 9% 15% 7% 2	4466
February	1st to 10th	Day	60% 2 10% 17% 10% 1	1893
	11th to 20th	Day	59% 2 9% 20% 10%	1958
	21st to end	Day	57% 2 10% 21% 9% 2	1650
March	1st to 10th	Day	60% 1 5% 20% 11% 2	4521
	11th to 20th	Day	43% 2 9% 29% 16% 1	4980
	21st to end	Day	53% 2 10% 21% 11% 3	5465
April	1st to 10th	Day	49% 3 10% 24% 13% 1	2360
	11th to 20th	Day	47% 2 10% 23% 14% 3	2437
	21st to end	Day	50% 2 9% 24% 12% 3	2600
May	1st to 10th	Day	56% 3 11% 19% 11% 1	5897
	11th to 20th	Day	51% 3 12% 25% 10%	5865
	21st to end	Day	47% 3 12% 25% 12% 1	6447
June	1st to 10th	Day	41% 4 11% 25% 18% 2	2620
	11th to 20th	Day	39% 4 14% 24% 18% 2	2800
	21st to end	Day	39% 5% 14% 22% 17% 4	2800
July	1st to 10th	Day	40% 4 11% 27% 18% 1	6291
	11th to 20th	Day	40% 5% 13% 27% 15% 1	6104
	21st to end	Day	45% 5% 14% 20% 14% 3	6240
August	1st to 10th	Day	35% 4 15% 32% 12% 1	4221
	11th to 20th	Day	35% 4 10% 33% 16% 1	4213
	21st to end	Day	29% 3 13% 32% 20% 3	4357
September	1st to 10th	Day	35% 2 10% 27% 20% 5%	2276
	11th to 20th	Day	33% 2 10% 28% 24% 3	2178
	21st to end	Day	40% 3 9% 24% 22% 2	2090
October	1st to 10th	Day	24% 3 8% 32% 31% 2	3480
	11th to 20th	Day	31% 2 8% 31% 26% 2	3177
	21st to end	Day	38% 1 10% 25% 23% 2	3180
November	1st to 10th	Day	36% 3 8% 30% 20% 3	1762
	11th to 20th	Day	49% 2 8% 22% 15% 3	1800
	21st to end	Day	53% 2 9% 24% 12% 1	1800
December	1st to 10th	Day	53% 2 8% 27% 10%	2930
	11th to 20th	Day	63% 2 8% 20% 7%	3370
	21st to end	Day	71% 2 9% 12% 6%	4219
January	1st to 10th	Night	69% 2 7% 14% 8%	6348
	11th to 20th	Night	69% 2 7% 12% 8% 2	6058
	21st to end	Night	60% 2 8% 20% 9% 1	6490
February	1st to 10th	Night	60% 2 9% 20% 8% 1	2505
	11th to 20th	Night	56% 3 8% 20% 13% 1	2339
	21st to end	Night	57% 2 10% 18% 11% 2	1980
March	1st to 10th	Night	52% 2 5% 28% 11% 2	5332
	11th to 20th	Night	41% 2 10% 30% 16% 1	4980
	21st to end	Night	52% 2 7% 26% 11% 2	5467
April	1st to 10th	Night	46% 3 10% 26% 12% 2	2057
	11th to 20th	Night	43% 3 11% 20% 19% 5%	1912
	21st to end	Night	45% 3 11% 24% 14% 3	1800
May	1st to 10th	Night	58% 3 9% 20% 8% 3	4060
	11th to 20th	Night	46% 4 13% 26% 11% 1	4033
	21st to end	Night	43% 3 14% 26% 11% 3	4429
June	1st to 10th	Night	35% 3 9% 28% 22% 2	1774
	11th to 20th	Night	33% 5% 15% 23% 19% 4	1600
	21st to end	Night	31% 6% 18% 22% 19% 5%	1600
July	1st to 10th	Night	36% 4 11% 26% 19% 5%	3580
	11th to 20th	Night	37% 5% 15% 28% 15% 1	3742
	21st to end	Night	39% 4 12% 26% 15% 3	4297
August	1st to 10th	Night	37% 4 14% 31% 13% 1	2904
	11th to 20th	Night	35% 4 11% 31% 18% 1	2902
	21st to end	Night	25% 4 15% 31% 23% 3	3536
September	1st to 10th	Night	33% 3 12% 26% 19% 6%	2102
	11th to 20th	Night	28% 3 8% 29% 29% 4	2179
	21st to end	Night	38% 3 8% 23% 26% 3	2090
October	1st to 10th	Night	22% 2 6% 32% 35% 3	3480
	11th to 20th	Night	30% 2 9% 27% 31% 2	3741
	21st to end	Night	35% 2 7% 24% 27% 4	4364
November	1st to 10th	Night	40% 2 10% 24% 22% 3	2536
	11th to 20th	Night	46% 2 7% 24% 18% 3	2600
	21st to end	Night	56% 2 11% 21% 10% 1	2600
December	1st to 10th	Night	51% 2 11% 26% 10%	4250
	11th to 20th	Night	62% 2 9% 19% 8%	4824
	21st to end	Night	73% 2 8% 14% 4	6743

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	29% 16% 33% 17% 5%	300
	11th to 20th	Day	30% 20% 32% 15% 3	300
	21st to end	Day	33% 16% 31% 17% 3	330
February	1st to 10th	Day	29% 19% 32% 17% 3	300
	11th to 20th	Day	29% 23% 32% 14% 2	300
	21st to end	Day	28% 16% 44% 9% 2	249
March	1st to 10th	Day	26% 19% 36% 16% 3	315
	11th to 20th	Day	26% 12% 34% 20% 7% 1	500
	21st to end	Day	30% 13% 30% 20% 7%	550
April	1st to 10th	Day	25% 14% 29% 22% 9% 2	500
	11th to 20th	Day	22% 17% 25% 21% 11% 4	492
	21st to end	Day	23% 11% 32% 22% 10% 2	500
May	1st to 10th	Day	26% 8% 31% 22% 9% 4	503
	11th to 20th	Day	24% 7% 22% 24% 16% 7%	527
	21st to end	Day	14% 6% 21% 30% 16% 12%	573
June	1st to 10th	Day	15% 4 20% 29% 22% 10%	550
	11th to 20th	Day	11% 3 21% 32% 24% 8%	730
	21st to end	Day	12% 4 22% 31% 23% 9%	730
July	1st to 10th	Day	14% 1 13% 29% 24% 19%	721
	11th to 20th	Day	13% 3 18% 27% 27% 13%	641
	21st to end	Day	13% 2 14% 28% 28% 15%	576
August	1st to 10th	Day	11% 2 14% 25% 29% 19%	526
	11th to 20th	Day	13% 2 15% 29% 27% 14%	519
	21st to end	Day	11% 2 12% 28% 30% 16%	583
September	1st to 10th	Day	12% 4 12% 26% 35% 12%	530
	11th to 20th	Day	10% 2 11% 28% 34% 16%	522
	21st to end	Day	19% 7% 18% 24% 20% 11%	490
October	1st to 10th	Day	11% 5% 21% 34% 20% 9%	490
	11th to 20th	Day	16% 11% 30% 25% 15% 4	490
	21st to end	Day	28% 8% 35% 21% 7% 1	392
November	1st to 10th	Day	11% 13% 37% 23% 12% 4	300
	11th to 20th	Day	23% 14% 33% 18% 9% 3	300
	21st to end	Day	26% 10% 39% 20% 5%	300
December	1st to 10th	Day	25% 13% 38% 18% 5% 1	300
	11th to 20th	Day	27% 15% 37% 15% 6% 1	300
	21st to end	Day	32% 12% 34% 17% 4 1	330
January	1st to 10th	Night	24% 13% 32% 25% 6% 1	1000
	11th to 20th	Night	31% 12% 32% 23% 3	867
	21st to end	Night	24% 12% 33% 28% 4	880
February	1st to 10th	Night	29% 10% 32% 27% 3	800
	11th to 20th	Night	24% 14% 35% 25% 3	783
	21st to end	Night	28% 10% 33% 27% 2	660
March	1st to 10th	Night	23% 10% 34% 26% 6% 1	800
	11th to 20th	Night	22% 11% 33% 27% 7% 1	800
	21st to end	Night	24% 10% 29% 30% 8%	880
April	1st to 10th	Night	21% 9% 33% 29% 8%	657
	11th to 20th	Night	20% 8% 32% 28% 11% 1	593
	21st to end	Night	18% 5% 35% 32% 9% 1	600
May	1st to 10th	Night	26% 5% 27% 29% 13% 1	600
	11th to 20th	Night	19% 3 21% 35% 19% 3	591
	21st to end	Night	11% 2 20% 37% 27% 3	650
June	1st to 10th	Night	11% 2 17% 45% 24% 2	600
	11th to 20th	Night	12% 2 13% 46% 25% 3	600
	21st to end	Night	8% 1 17% 45% 26% 3	600
July	1st to 10th	Night	12% 2 9% 38% 31% 9%	585
	11th to 20th	Night	8% 1 11% 42% 31% 7%	582
	21st to end	Night	11% 2 8% 39% 36% 4	657
August	1st to 10th	Night	10% 2 8% 39% 37% 3	597
	11th to 20th	Night	9% 1 10% 42% 34% 5%	594
	21st to end	Night	7% 2 11% 35% 39% 7%	660
September	1st to 10th	Night	14% 2 11% 34% 34% 5%	702
	11th to 20th	Night	11% 2 11% 35% 36% 5%	793
	21st to end	Night	17% 3 17% 34% 25% 3	760
October	1st to 10th	Night	12% 3 21% 37% 24% 4	760
	11th to 20th	Night	19% 7% 25% 33% 15% 1	760
	21st to end	Night	22% 7% 30% 29% 11%	836
November	1st to 10th	Night	18% 6% 27% 32% 15% 1	780
	11th to 20th	Night	22% 10% 30% 28% 10% 1	800
	21st to end	Night	25% 8% 27% 31% 8% 1	800
December	1st to 10th	Night	27% 9% 32% 25% 6% 1	800
	11th to 20th	Night	26% 8% 33% 27% 6% 1	800
	21st to end	Night	32% 11% 28% 25% 4	990

Page generated at 2025-09-16 01:49:17. Version ac07

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