Caumsett State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caumsett State Park clear sky chart from 2005-11-06 to 2024-12-24.

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% 7% 2 6% 4 4 4 4 6% 7% 41%	101681
	Night	17% 8% 2 6% 4 4 4 3 5% 6% 41%	98431
Transparency	Day	41% 6% 12% 23% 16% 2	105226
	Night	42% 5% 11% 23% 16% 2	102975
Seeing	Day	18% 11% 29% 27% 13% 2	15158
	Night	19% 11% 31% 27% 9% 1	24315

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% 7% 2 5% 4 3 3 3 5% 6% 47%	2517
	11th to 20th	Day	16% 9% 2 6% 5% 5% 5% 4 5% 6% 37%	2520
	21st to end	Day	21% 10% 4 8% 4 5% 5% 3 5% 5% 32%	2941
February	1st to 10th	Day	17% 7% 3 6% 4 4 4 4 5% 7% 40%	1753
	11th to 20th	Day	15% 5% 2 7% 4 4 4 3 4 7% 45%	1848
	21st to end	Day	19% 7% 2 6% 4 4 4 3 5% 6% 39%	1570
March	1st to 10th	Day	26% 9% 2 5% 4 3 3 3 4 5% 37%	3116
	11th to 20th	Day	9% 5% 1 4 4 4 6% 4 7% 9% 46%	3291
	21st to end	Day	20% 7% 2 5% 4 3 4 3 4 5% 43%	4166
April	1st to 10th	Day	17% 8% 2 6% 5% 4 4 3 6% 7% 39%	2280
	11th to 20th	Day	17% 6% 2 6% 4 4 4 3 5% 7% 43%	2254
	21st to end	Day	19% 6% 2 4 4 4 4 3 5% 7% 42%	2338
May	1st to 10th	Day	25% 9% 3 6% 3 3 4 3 5% 8% 32%	4106
	11th to 20th	Day	22% 8% 3 6% 4 4 4 4 5% 7% 34%	4297
	21st to end	Day	13% 5% 2 5% 3 4 3 3 6% 9% 47%	4837
June	1st to 10th	Day	16% 6% 2 5% 4 4 4 4 6% 9% 41%	2660
	11th to 20th	Day	13% 6% 2 5% 5% 4 5% 4 6% 9% 40%	2660
	21st to end	Day	10% 7% 2 6% 4 4 5% 4 6% 9% 43%	2660
July	1st to 10th	Day	8% 6% 3 7% 5% 5% 6% 6% 7% 9% 37%	4440
	11th to 20th	Day	9% 7% 3 6% 5% 4 5% 5% 7% 10% 41%	4440
	21st to end	Day	13% 8% 3 8% 5% 5% 5% 5% 6% 8% 34%	4814
August	1st to 10th	Day	17% 7% 3 7% 4 5% 5% 4 7% 10% 33%	4191
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 9% 43%	3730
	21st to end	Day	8% 5% 2 6% 4 4 4 4 6% 10% 47%	4180
September	1st to 10th	Day	13% 5% 2 6% 4 4 4 3 5% 7% 47%	2280
	11th to 20th	Day	11% 5% 2 4 3 4 4 3 5% 7% 52%	2171
	21st to end	Day	18% 6% 3 7% 4 4 4 3 5% 6% 42%	2090
October	1st to 10th	Day	19% 8% 2 5% 3 3 3 4 4 7% 43%	2026
	11th to 20th	Day	13% 6% 2 5% 4 4 4 4 4 6% 48%	1900
	21st to end	Day	19% 6% 2 5% 4 4 4 3 4 7% 42%	1905
November	1st to 10th	Day	13% 6% 2 5% 4 3 3 3 5% 6% 51%	1761
	11th to 20th	Day	16% 7% 2 5% 2 3 3 3 4 6% 49%	1800
	21st to end	Day	15% 7% 2 5% 4 3 5% 3 5% 6% 45%	1757
December	1st to 10th	Day	17% 7% 3 6% 5% 4 4 4 7% 7% 37%	1600
	11th to 20th	Day	22% 6% 2 5% 2 2 3 3 4 6% 45%	1986
	21st to end	Day	17% 9% 3 8% 5% 5% 5% 4 5% 6% 33%	2796
January	1st to 10th	Night	17% 7% 2 5% 3 3 3 2 5% 6% 46%	4429
	11th to 20th	Night	16% 9% 3 7% 3 4 3 3 4 5% 44%	4440
	21st to end	Night	24% 11% 3 7% 4 3 3 3 5% 6% 32%	4712
February	1st to 10th	Night	16% 10% 3 5% 4 4 3 3 5% 5% 42%	2425
	11th to 20th	Night	17% 8% 3 5% 4 3 4 3 5% 7% 40%	2218
	21st to end	Night	20% 7% 2 5% 4 4 4 3 4 5% 41%	1884
March	1st to 10th	Night	23% 11% 3 6% 3 3 3 3 4 5% 36%	3724
	11th to 20th	Night	12% 6% 2 7% 5% 4 4 3 6% 6% 45%	3664
	21st to end	Night	21% 9% 2 5% 4 3 3 3 5% 5% 40%	3466
April	1st to 10th	Night	18% 8% 2 6% 4 5% 4 4 5% 6% 38%	1900
	11th to 20th	Night	18% 7% 2 6% 4 4 3 4 4 7% 40%	1875
	21st to end	Night	18% 7% 3 6% 5% 3 4 3 4 6% 42%	1840
May	1st to 10th	Night	24% 10% 4 7% 5% 4 3 3 5% 7% 29%	2834
	11th to 20th	Night	23% 9% 3 7% 5% 4 3 4 5% 5% 32%	2624
	21st to end	Night	16% 8% 2 5% 4 3 4 3 5% 7% 43%	2738
June	1st to 10th	Night	16% 7% 2 6% 4 3 4 5% 5% 7% 41%	1520
	11th to 20th	Night	13% 7% 3 6% 3 4 4 4 8% 8% 41%	1520
	21st to end	Night	10% 5% 2 6% 4 5% 6% 4 7% 10% 40%	1520
July	1st to 10th	Night	10% 8% 3 8% 6% 5% 6% 5% 7% 9% 34%	2520
	11th to 20th	Night	11% 7% 3 7% 4 6% 5% 5% 8% 9% 36%	2520
	21st to end	Night	16% 9% 3 7% 4 4 4 3 7% 10% 33%	2739
August	1st to 10th	Night	21% 7% 2 7% 5% 4 5% 4 7% 7% 31%	2688
	11th to 20th	Night	13% 7% 3 7% 4 5% 5% 4 6% 8% 37%	3097
	21st to end	Night	8% 5% 2 5% 3 4 5% 3 6% 8% 51%	3476
September	1st to 10th	Night	14% 4 2 6% 4 4 4 4 6% 7% 44%	1900
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 5% 6% 52%	2007
	21st to end	Night	17% 5% 2 6% 5% 3 3 3 5% 6% 43%	2090
October	1st to 10th	Night	18% 8% 2 6% 4 4 3 3 4 6% 41%	2152
	11th to 20th	Night	14% 5% 2 5% 4 3 4 3 4 6% 50%	2280
	21st to end	Night	21% 6% 2 6% 3 3 3 3 4 6% 42%	2691
November	1st to 10th	Night	12% 5% 2 6% 4 4 4 3 5% 6% 50%	2537
	11th to 20th	Night	18% 7% 2 4 3 2 3 3 4 5% 48%	2600
	21st to end	Night	14% 6% 2 5% 4 4 3 4 5% 6% 46%	2640
December	1st to 10th	Night	20% 7% 2 5% 4 4 4 3 6% 6% 39%	2800
	11th to 20th	Night	20% 7% 2 5% 4 3 3 4 5% 6% 42%	3428
	21st to end	Night	19% 9% 3 6% 4 4 4 3 5% 5% 37%	4933

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% 9% 32% 13% 3	2518
	11th to 20th	Day	47% 4 10% 25% 11% 2	2520
	21st to end	Day	56% 4 8% 21% 10% 1	2941
February	1st to 10th	Day	45% 5% 12% 23% 13% 1	1753
	11th to 20th	Day	41% 4 10% 26% 17% 2	1857
	21st to end	Day	48% 4 10% 21% 14% 3	1570
March	1st to 10th	Day	50% 6% 10% 22% 11% 2	3119
	11th to 20th	Day	31% 8% 13% 32% 14% 1	3291
	21st to end	Day	44% 4 8% 18% 21% 6%	4166
April	1st to 10th	Day	44% 6% 9% 22% 16% 4	2280
	11th to 20th	Day	42% 6% 10% 22% 17% 3	2254
	21st to end	Day	42% 6% 10% 22% 17% 4	2338
May	1st to 10th	Day	52% 5% 15% 15% 12% 1	4120
	11th to 20th	Day	50% 7% 14% 19% 9% 2	4301
	21st to end	Day	34% 8% 13% 26% 18% 2	4837
June	1st to 10th	Day	40% 7% 12% 23% 15% 1	2660
	11th to 20th	Day	41% 6% 14% 25% 12% 2	2660
	21st to end	Day	38% 8% 16% 23% 15% 1	2660
July	1st to 10th	Day	41% 10% 13% 20% 16% 1	4370
	11th to 20th	Day	38% 7% 18% 22% 13% 1	4365
	21st to end	Day	46% 7% 13% 17% 15% 2	4661
August	1st to 10th	Day	46% 7% 16% 22% 8%	4177
	11th to 20th	Day	37% 7% 13% 32% 10% 1	3766
	21st to end	Day	32% 6% 13% 27% 20% 1	4180
September	1st to 10th	Day	37% 6% 13% 22% 19% 2	2280
	11th to 20th	Day	33% 5% 11% 25% 24% 2	2171
	21st to end	Day	44% 6% 9% 20% 19% 3	2090
October	1st to 10th	Day	34% 7% 11% 19% 24% 5%	3364
	11th to 20th	Day	27% 4 10% 23% 32% 5%	3140
	21st to end	Day	29% 4 14% 25% 24% 3	3117
November	1st to 10th	Day	36% 4 13% 23% 22% 2	1761
	11th to 20th	Day	38% 3 10% 23% 23% 3	1800
	21st to end	Day	39% 5% 14% 28% 12% 2	1757
December	1st to 10th	Day	44% 5% 15% 21% 14% 1	1600
	11th to 20th	Day	42% 4 13% 23% 16% 2	1986
	21st to end	Day	51% 6% 11% 24% 9%	2796
January	1st to 10th	Night	40% 3 11% 30% 12% 4	4429
	11th to 20th	Night	44% 4 12% 24% 13% 2	4440
	21st to end	Night	54% 3 8% 22% 12% 1	4712
February	1st to 10th	Night	44% 4 12% 24% 13% 2	2425
	11th to 20th	Night	44% 5% 9% 20% 17% 5%	2220
	21st to end	Night	44% 4 7% 24% 16% 4	1884
March	1st to 10th	Night	52% 3 9% 22% 11% 3	3734
	11th to 20th	Night	38% 5% 12% 27% 15% 3	3665
	21st to end	Night	46% 4 6% 15% 22% 6%	3466
April	1st to 10th	Night	47% 5% 9% 18% 17% 3	1900
	11th to 20th	Night	45% 5% 9% 18% 21% 1	1875
	21st to end	Night	44% 5% 9% 21% 17% 5%	1840
May	1st to 10th	Night	55% 6% 12% 16% 10% 1	2840
	11th to 20th	Night	55% 5% 14% 16% 9% 1	2625
	21st to end	Night	41% 6% 13% 24% 14% 2	2739
June	1st to 10th	Night	42% 6% 10% 22% 19% 1	1520
	11th to 20th	Night	39% 7% 15% 27% 12% 1	1520
	21st to end	Night	38% 9% 13% 26% 13% 1	1520
July	1st to 10th	Night	45% 9% 15% 18% 12% 1	2480
	11th to 20th	Night	42% 8% 15% 24% 11% 1	2472
	21st to end	Night	46% 7% 15% 16% 15% 2	2651
August	1st to 10th	Night	50% 6% 17% 17% 9% 1	2678
	11th to 20th	Night	41% 7% 14% 28% 9% 1	3127
	21st to end	Night	30% 6% 13% 32% 18% 1	3476
September	1st to 10th	Night	39% 6% 10% 25% 18% 1	1900
	11th to 20th	Night	33% 5% 10% 25% 22% 3	2007
	21st to end	Night	43% 6% 7% 21% 20% 3	2090
October	1st to 10th	Night	40% 5% 11% 23% 19% 2	3594
	11th to 20th	Night	23% 4 10% 28% 31% 4	3779
	21st to end	Night	31% 4 13% 29% 21% 3	4429
November	1st to 10th	Night	36% 5% 10% 24% 21% 4	2537
	11th to 20th	Night	40% 4 8% 24% 20% 4	2600
	21st to end	Night	38% 4 12% 30% 14% 2	2640
December	1st to 10th	Night	45% 4 12% 23% 14% 1	2800
	11th to 20th	Night	44% 4 12% 21% 17% 2	3428
	21st to end	Night	47% 5% 10% 25% 11% 1	4933

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	22% 21% 34% 19% 4	180
	11th to 20th	Day	16% 30% 34% 17% 3	180
	21st to end	Day	19% 15% 42% 18% 5% 1	247
February	1st to 10th	Day	24% 13% 44% 17% 2	313
	11th to 20th	Day	19% 20% 41% 18% 2	456
	21st to end	Day	24% 20% 32% 19% 5%	382
March	1st to 10th	Day	14% 21% 38% 22% 4	460
	11th to 20th	Day	17% 16% 40% 23% 4 1	460
	21st to end	Day	23% 16% 36% 18% 6% 1	506
April	1st to 10th	Day	21% 18% 36% 17% 8% 1	460
	11th to 20th	Day	20% 14% 33% 23% 9% 1	452
	21st to end	Day	25% 12% 34% 23% 6% 1	460
May	1st to 10th	Day	27% 12% 31% 22% 7% 1	463
	11th to 20th	Day	18% 10% 30% 33% 9% 1	487
	21st to end	Day	16% 4 22% 33% 22% 2	529
June	1st to 10th	Day	18% 6% 23% 35% 17% 2	490
	11th to 20th	Day	14% 7% 29% 33% 14% 2	490
	21st to end	Day	12% 4 29% 32% 19% 2	490
July	1st to 10th	Day	11% 4 20% 37% 23% 5%	485
	11th to 20th	Day	9% 4 21% 36% 24% 5%	484
	21st to end	Day	13% 5% 21% 40% 19% 3	532
August	1st to 10th	Day	12% 6% 19% 36% 22% 6%	486
	11th to 20th	Day	14% 3 19% 37% 24% 3	479
	21st to end	Day	11% 5% 23% 36% 20% 6%	539
September	1st to 10th	Day	17% 6% 24% 26% 21% 6%	490
	11th to 20th	Day	14% 4 21% 30% 22% 9%	490
	21st to end	Day	22% 6% 27% 27% 14% 4	490
October	1st to 10th	Day	25% 7% 24% 23% 16% 4	490
	11th to 20th	Day	14% 13% 31% 26% 13% 2	490
	21st to end	Day	20% 13% 32% 24% 10% 2	442
November	1st to 10th	Day	15% 13% 29% 31% 10% 2	395
	11th to 20th	Day	19% 20% 33% 22% 6% 1	400
	21st to end	Day	19% 18% 32% 24% 7% 1	357
December	1st to 10th	Day	21% 17% 39% 19% 6% 1	200
	11th to 20th	Day	27% 25% 30% 16% 4	200
	21st to end	Day	21% 21% 37% 14% 7%	204
January	1st to 10th	Night	19% 19% 39% 20% 4	760
	11th to 20th	Night	24% 17% 33% 24% 2	760
	21st to end	Night	19% 17% 41% 21% 2	836
February	1st to 10th	Night	20% 16% 40% 23% 2	760
	11th to 20th	Night	22% 19% 39% 18% 2	743
	21st to end	Night	23% 18% 35% 19% 4	628
March	1st to 10th	Night	21% 16% 36% 21% 5%	760
	11th to 20th	Night	20% 14% 41% 21% 4 1	760
	21st to end	Night	21% 15% 39% 20% 4	836
April	1st to 10th	Night	23% 14% 36% 22% 4 1	760
	11th to 20th	Night	20% 14% 33% 27% 6%	751
	21st to end	Night	21% 10% 35% 27% 6% 1	700
May	1st to 10th	Night	24% 9% 33% 27% 7% 1	570
	11th to 20th	Night	22% 9% 36% 27% 6%	451
	21st to end	Night	20% 6% 19% 38% 14% 2	411
June	1st to 10th	Night	19% 7% 24% 34% 15%	380
	11th to 20th	Night	16% 5% 22% 41% 15% 1	380
	21st to end	Night	10% 5% 23% 49% 12% 1	380
July	1st to 10th	Night	11% 4 24% 42% 18% 1	370
	11th to 20th	Night	11% 6% 19% 42% 19% 2	368
	21st to end	Night	13% 3 21% 45% 16% 1	416
August	1st to 10th	Night	12% 3 21% 44% 18% 1	482
	11th to 20th	Night	14% 3 18% 37% 26% 2	750
	21st to end	Night	13% 5% 18% 38% 24% 3	836
September	1st to 10th	Night	15% 4 26% 35% 18% 3	760
	11th to 20th	Night	15% 5% 21% 34% 20% 5%	760
	21st to end	Night	21% 5% 24% 31% 17% 2	760
October	1st to 10th	Night	21% 8% 26% 27% 14% 3	760
	11th to 20th	Night	17% 11% 29% 30% 12% 1	760
	21st to end	Night	23% 11% 34% 24% 7%	836
November	1st to 10th	Night	14% 11% 34% 28% 10% 2	780
	11th to 20th	Night	21% 15% 34% 22% 8%	800
	21st to end	Night	18% 17% 34% 25% 6% 1	800
December	1st to 10th	Night	25% 16% 34% 19% 5% 1	800
	11th to 20th	Night	23% 15% 37% 21% 4	800
	21st to end	Night	23% 14% 39% 21% 3	851

Page generated at 2024-12-21 04:13:52. Version ac07

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