Hamlin Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hamlin Beach State Park clear sky chart from 2005-11-06 to 2025-02-21.

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% 11% 4 9% 6% 5% 4 4 5% 7% 30%	108779
	Night	16% 12% 5% 11% 6% 5% 5% 4 5% 6% 27%	109795
Transparency	Day	51% 8% 13% 19% 9% 1	112409
	Night	55% 7% 12% 17% 8% 1	114328
Seeing	Day	20% 15% 29% 24% 10% 3	14798
	Night	21% 16% 29% 24% 10% 1	24261

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	13% 19% 10% 18% 8% 5% 4 3 3 4 14%	3597
	11th to 20th	Day	11% 25% 9% 18% 9% 6% 5% 4 3 3 7%	3730
	21st to end	Day	17% 18% 8% 15% 8% 6% 5% 4 4 4 11%	4466
February	1st to 10th	Day	15% 18% 5% 15% 8% 6% 5% 4 5% 4 15%	1800
	11th to 20th	Day	12% 16% 9% 17% 9% 5% 5% 3 4 3 16%	1753
	21st to end	Day	19% 16% 5% 14% 8% 6% 4 4 4 5% 16%	1507
March	1st to 10th	Day	18% 12% 5% 11% 5% 4 4 3 4 5% 29%	3361
	11th to 20th	Day	11% 16% 4 9% 6% 5% 5% 4 5% 6% 28%	3480
	21st to end	Day	14% 12% 5% 10% 5% 4 4 4 6% 6% 31%	3865
April	1st to 10th	Day	16% 13% 4 8% 5% 4 4 3 5% 6% 32%	2280
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 3 4 5% 37%	2254
	21st to end	Day	19% 10% 3 7% 5% 5% 4 3 4 6% 33%	2437
May	1st to 10th	Day	19% 8% 3 7% 5% 4 4 3 5% 6% 35%	4222
	11th to 20th	Day	16% 9% 3 8% 5% 5% 4 4 6% 7% 34%	4398
	21st to end	Day	10% 5% 2 7% 4 4 5% 4 6% 8% 45%	4837
June	1st to 10th	Day	14% 7% 3 6% 5% 5% 4 4 6% 8% 38%	2660
	11th to 20th	Day	12% 5% 2 6% 5% 4 5% 5% 6% 10% 40%	2660
	21st to end	Day	13% 5% 3 6% 5% 4 4 4 6% 8% 42%	2660
July	1st to 10th	Day	10% 4 2 5% 4 4 5% 4 7% 10% 45%	4440
	11th to 20th	Day	9% 5% 2 6% 4 5% 4 4 7% 9% 43%	4440
	21st to end	Day	8% 4 2 7% 5% 5% 5% 5% 7% 10% 41%	4663
August	1st to 10th	Day	16% 6% 3 6% 4 5% 4 4 6% 7% 39%	4104
	11th to 20th	Day	13% 6% 3 7% 5% 5% 6% 4 6% 9% 36%	4044
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	4226
September	1st to 10th	Day	13% 6% 2 6% 4 4 5% 4 6% 8% 42%	2280
	11th to 20th	Day	13% 6% 1 6% 5% 4 3 3 6% 8% 44%	2269
	21st to end	Day	16% 6% 3 7% 5% 6% 6% 3 5% 8% 35%	1989
October	1st to 10th	Day	21% 8% 3 7% 5% 4 4 4 6% 5% 33%	1900
	11th to 20th	Day	18% 10% 4 9% 5% 5% 5% 3 6% 6% 28%	1900
	21st to end	Day	25% 13% 3 9% 6% 4 4 3 4 5% 23%	2090
November	1st to 10th	Day	13% 13% 4 9% 6% 4 5% 4 5% 6% 29%	1721
	11th to 20th	Day	13% 17% 4 11% 5% 6% 4 4 6% 6% 24%	1600
	21st to end	Day	20% 18% 5% 10% 6% 5% 5% 3 5% 7% 17%	1600
December	1st to 10th	Day	18% 21% 7% 12% 7% 6% 5% 4 5% 5% 10%	2600
	11th to 20th	Day	20% 19% 7% 13% 5% 3 3 3 4 4 18%	2986
	21st to end	Day	21% 21% 7% 15% 8% 4 3 3 4 4 10%	3960
January	1st to 10th	Night	15% 18% 7% 23% 7% 5% 4 2 4 4 11%	6349
	11th to 20th	Night	10% 19% 9% 18% 9% 6% 6% 4 5% 5% 10%	6150
	21st to end	Night	17% 18% 6% 15% 8% 5% 5% 3 4 5% 13%	6490
February	1st to 10th	Night	15% 18% 5% 14% 7% 5% 5% 4 5% 5% 17%	2600
	11th to 20th	Night	13% 13% 7% 16% 9% 6% 5% 3 5% 4 18%	2533
	21st to end	Night	16% 15% 6% 15% 6% 6% 3 3 6% 6% 19%	1947
March	1st to 10th	Night	20% 12% 4 10% 5% 4 4 3 4 4 29%	3474
	11th to 20th	Night	17% 14% 4 10% 6% 4 4 4 5% 7% 25%	3479
	21st to end	Night	15% 9% 3 11% 4 4 4 4 5% 5% 35%	3766
April	1st to 10th	Night	20% 12% 3 7% 6% 3 5% 4 4 6% 29%	1900
	11th to 20th	Night	16% 10% 2 7% 5% 4 5% 4 5% 7% 35%	1875
	21st to end	Night	18% 9% 3 7% 4 3 5% 5% 6% 8% 33%	1759
May	1st to 10th	Night	23% 10% 3 7% 3 4 4 3 5% 6% 32%	2719
	11th to 20th	Night	17% 8% 2 7% 5% 4 4 4 6% 8% 35%	2495
	21st to end	Night	10% 5% 2 6% 4 4 4 4 6% 9% 45%	2738
June	1st to 10th	Night	13% 6% 2 7% 5% 5% 5% 5% 7% 9% 35%	1520
	11th to 20th	Night	10% 6% 3 6% 5% 5% 5% 4 7% 9% 41%	1520
	21st to end	Night	12% 5% 3 7% 5% 5% 5% 4 5% 8% 40%	1520
July	1st to 10th	Night	11% 6% 2 7% 4 4 4 4 6% 8% 42%	2520
	11th to 20th	Night	10% 6% 2 6% 5% 4 5% 5% 6% 9% 43%	2520
	21st to end	Night	10% 5% 2 5% 3 4 5% 3 7% 8% 47%	2886
August	1st to 10th	Night	11% 7% 2 6% 4 4 5% 4 5% 10% 42%	2825
	11th to 20th	Night	13% 7% 3 7% 4 5% 4 4 6% 8% 39%	2785
	21st to end	Night	9% 4 2 6% 5% 4 6% 5% 7% 9% 44%	3398
September	1st to 10th	Night	13% 5% 2 6% 4 3 4 4 6% 7% 45%	1900
	11th to 20th	Night	14% 5% 2 5% 4 4 4 3 5% 8% 47%	1909
	21st to end	Night	17% 7% 2 6% 5% 4 5% 4 7% 8% 36%	2190
October	1st to 10th	Night	18% 8% 2 7% 6% 5% 5% 4 6% 6% 33%	2280
	11th to 20th	Night	22% 9% 3 8% 5% 4 4 4 5% 6% 29%	2280
	21st to end	Night	26% 12% 3 7% 4 4 4 5% 4 5% 25%	2508
November	1st to 10th	Night	15% 11% 3 7% 5% 4 5% 5% 5% 6% 34%	2576
	11th to 20th	Night	15% 13% 5% 9% 6% 5% 5% 3 6% 7% 25%	2800
	21st to end	Night	19% 15% 6% 10% 6% 5% 5% 4 6% 6% 20%	2800
December	1st to 10th	Night	16% 19% 9% 15% 8% 6% 5% 4 5% 4 9%	4580
	11th to 20th	Night	18% 20% 6% 12% 6% 5% 4 3 5% 4 17%	5208
	21st to end	Night	24% 19% 7% 12% 7% 5% 4 3 4 4 12%	6996

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	72% 7% 9% 9% 2	3598
	11th to 20th	Day	79% 7% 7% 4 2 1	3761
	21st to end	Day	75% 7% 12% 5% 2	4466
February	1st to 10th	Day	70% 8% 11% 11% 1	1800
	11th to 20th	Day	72% 7% 8% 11% 2	1762
	21st to end	Day	69% 6% 10% 10% 5%	1507
March	1st to 10th	Day	57% 7% 9% 20% 7%	3364
	11th to 20th	Day	53% 10% 14% 14% 8% 1	3480
	21st to end	Day	50% 8% 11% 22% 8% 1	3865
April	1st to 10th	Day	53% 6% 11% 18% 10% 2	2280
	11th to 20th	Day	48% 6% 10% 20% 14% 2	2254
	21st to end	Day	51% 7% 9% 17% 13% 2	2437
May	1st to 10th	Day	49% 7% 12% 19% 12% 2	4234
	11th to 20th	Day	48% 10% 15% 18% 8% 1	4402
	21st to end	Day	35% 9% 13% 25% 16% 2	4837
June	1st to 10th	Day	43% 8% 12% 20% 17% 1	2660
	11th to 20th	Day	37% 8% 14% 24% 16% 1	2660
	21st to end	Day	39% 8% 14% 23% 16% 1	2660
July	1st to 10th	Day	34% 7% 14% 30% 15% 1	4370
	11th to 20th	Day	34% 9% 15% 29% 13%	4365
	21st to end	Day	36% 10% 16% 25% 13%	4514
August	1st to 10th	Day	43% 8% 15% 22% 12% 1	4091
	11th to 20th	Day	43% 8% 16% 25% 7%	4083
	21st to end	Day	36% 7% 14% 33% 9% 1	4226
September	1st to 10th	Day	39% 8% 14% 26% 12% 1	2280
	11th to 20th	Day	38% 6% 13% 28% 14%	2269
	21st to end	Day	47% 7% 13% 22% 10% 1	1989
October	1st to 10th	Day	40% 8% 16% 24% 11%	3160
	11th to 20th	Day	46% 6% 16% 19% 12%	3140
	21st to end	Day	50% 7% 15% 22% 6% 1	3428
November	1st to 10th	Day	53% 8% 12% 17% 9% 1	1721
	11th to 20th	Day	58% 8% 14% 13% 6% 1	1600
	21st to end	Day	66% 7% 12% 12% 3	1600
December	1st to 10th	Day	73% 7% 13% 6% 1	2600
	11th to 20th	Day	70% 6% 10% 7% 7% 1	2986
	21st to end	Day	77% 6% 10% 6% 2	3960
January	1st to 10th	Night	74% 8% 9% 7% 1	6349
	11th to 20th	Night	73% 8% 9% 7% 2	6194
	21st to end	Night	72% 6% 10% 6% 6%	6490
February	1st to 10th	Night	66% 7% 11% 13% 2	2600
	11th to 20th	Night	67% 6% 11% 12% 3	2535
	21st to end	Night	63% 7% 12% 14% 4	1947
March	1st to 10th	Night	57% 6% 11% 21% 5%	3484
	11th to 20th	Night	57% 8% 14% 15% 7%	3480
	21st to end	Night	46% 9% 10% 22% 12% 1	3766
April	1st to 10th	Night	56% 6% 9% 19% 9% 1	1900
	11th to 20th	Night	48% 7% 12% 18% 13% 2	1875
	21st to end	Night	47% 8% 11% 19% 13% 2	1759
May	1st to 10th	Night	52% 7% 11% 17% 11% 2	2726
	11th to 20th	Night	44% 9% 17% 19% 9% 2	2496
	21st to end	Night	33% 8% 14% 22% 21% 2	2739
June	1st to 10th	Night	41% 8% 13% 22% 14% 2	1520
	11th to 20th	Night	38% 7% 13% 22% 18% 2	1520
	21st to end	Night	41% 8% 13% 21% 16% 1	1520
July	1st to 10th	Night	38% 7% 14% 22% 18% 2	2480
	11th to 20th	Night	35% 6% 14% 29% 15% 1	2472
	21st to end	Night	33% 7% 16% 27% 16% 1	2794
August	1st to 10th	Night	37% 7% 15% 28% 13% 1	2814
	11th to 20th	Night	41% 7% 17% 25% 9%	2812
	21st to end	Night	32% 8% 14% 33% 12% 1	3398
September	1st to 10th	Night	36% 7% 14% 29% 13% 2	1900
	11th to 20th	Night	36% 6% 13% 28% 16% 1	1909
	21st to end	Night	43% 8% 14% 23% 12% 1	2190
October	1st to 10th	Night	44% 7% 11% 24% 13% 1	3800
	11th to 20th	Night	48% 6% 14% 19% 12% 1	3779
	21st to end	Night	46% 6% 13% 25% 8% 1	4120
November	1st to 10th	Night	48% 8% 13% 20% 9% 2	2576
	11th to 20th	Night	56% 8% 13% 15% 7% 1	2800
	21st to end	Night	61% 8% 16% 12% 2	2800
December	1st to 10th	Night	74% 8% 11% 6% 1	4580
	11th to 20th	Night	67% 8% 8% 9% 7% 1	5208
	21st to end	Night	75% 6% 9% 8% 2	6996

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	27% 29% 29% 11% 6%	200
	11th to 20th	Day	29% 26% 34% 9% 2	235
	21st to end	Day	25% 26% 31% 15% 3	330
February	1st to 10th	Day	27% 28% 33% 11% 1	300
	11th to 20th	Day	25% 34% 33% 8%	300
	21st to end	Day	34% 21% 32% 13%	319
March	1st to 10th	Day	21% 23% 34% 18% 4	460
	11th to 20th	Day	25% 22% 32% 17% 3 1	460
	21st to end	Day	27% 19% 32% 15% 6% 1	506
April	1st to 10th	Day	24% 19% 33% 18% 5%	460
	11th to 20th	Day	27% 19% 29% 17% 8% 2	452
	21st to end	Day	22% 18% 34% 20% 6% 1	460
May	1st to 10th	Day	21% 11% 33% 24% 9% 3	463
	11th to 20th	Day	15% 9% 32% 30% 11% 2	487
	21st to end	Day	13% 8% 31% 29% 16% 3	529
June	1st to 10th	Day	17% 12% 29% 31% 10% 1	490
	11th to 20th	Day	14% 10% 27% 34% 12% 2	490
	21st to end	Day	14% 9% 34% 30% 12% 1	490
July	1st to 10th	Day	8% 7% 26% 35% 20% 5%	485
	11th to 20th	Day	14% 6% 25% 33% 19% 4	484
	21st to end	Day	10% 6% 28% 40% 13% 3	532
August	1st to 10th	Day	11% 7% 21% 36% 19% 6%	486
	11th to 20th	Day	11% 6% 23% 34% 21% 5%	479
	21st to end	Day	11% 7% 26% 33% 18% 5%	539
September	1st to 10th	Day	14% 10% 23% 30% 17% 6%	490
	11th to 20th	Day	12% 7% 20% 27% 22% 11%	490
	21st to end	Day	16% 12% 29% 24% 15% 5%	490
October	1st to 10th	Day	22% 12% 27% 21% 14% 4	490
	11th to 20th	Day	23% 19% 31% 16% 9% 2	490
	21st to end	Day	32% 16% 30% 18% 5%	539
November	1st to 10th	Day	21% 20% 32% 18% 7% 2	353
	11th to 20th	Day	21% 28% 33% 14% 3 2	200
	21st to end	Day	31% 23% 31% 13% 3	200
December	1st to 10th	Day	30% 25% 27% 15% 3	200
	11th to 20th	Day	28% 30% 27% 13% 3	200
	21st to end	Day	32% 25% 27% 14% 1	220
January	1st to 10th	Night	25% 30% 29% 12% 4	800
	11th to 20th	Night	25% 27% 31% 15% 2	800
	21st to end	Night	21% 26% 33% 16% 4	880
February	1st to 10th	Night	27% 27% 31% 14% 1	800
	11th to 20th	Night	22% 28% 33% 15% 2	783
	21st to end	Night	24% 25% 32% 17% 2	629
March	1st to 10th	Night	24% 19% 35% 19% 4	760
	11th to 20th	Night	24% 22% 30% 20% 4	760
	21st to end	Night	21% 14% 34% 23% 7% 1	836
April	1st to 10th	Night	24% 15% 36% 22% 4	760
	11th to 20th	Night	22% 15% 31% 25% 7% 1	751
	21st to end	Night	24% 10% 29% 29% 9%	619
May	1st to 10th	Night	23% 6% 27% 28% 15% 1	508
	11th to 20th	Night	16% 5% 30% 38% 10%	374
	21st to end	Night	11% 5% 30% 34% 19% 1	411
June	1st to 10th	Night	13% 6% 30% 36% 15% 1	380
	11th to 20th	Night	12% 6% 27% 38% 17%	380
	21st to end	Night	12% 5% 26% 43% 13%	380
July	1st to 10th	Night	8% 4 23% 41% 22% 2	370
	11th to 20th	Night	11% 5% 25% 36% 22% 2	368
	21st to end	Night	11% 3 24% 42% 18% 3	501
August	1st to 10th	Night	11% 3 22% 40% 23% 3	567
	11th to 20th	Night	10% 5% 20% 35% 25% 3	564
	21st to end	Night	10% 4 23% 36% 25% 2	784
September	1st to 10th	Night	16% 6% 22% 30% 23% 3	760
	11th to 20th	Night	15% 5% 18% 29% 26% 6%	760
	21st to end	Night	17% 10% 21% 30% 17% 4	760
October	1st to 10th	Night	22% 10% 27% 23% 16% 2	760
	11th to 20th	Night	25% 15% 29% 22% 7% 1	760
	21st to end	Night	33% 13% 29% 22% 4	836
November	1st to 10th	Night	23% 15% 29% 25% 7% 1	780
	11th to 20th	Night	22% 24% 30% 17% 6% 1	800
	21st to end	Night	28% 21% 31% 15% 5%	800
December	1st to 10th	Night	31% 24% 29% 13% 3	800
	11th to 20th	Night	26% 26% 31% 15% 3	800
	21st to end	Night	33% 22% 30% 13% 2	880

Page generated at 2025-02-18 03:26:31. Version ac07

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