Hawn State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hawn State Park clear sky chart from 2005-11-06 to 2026-06-16.

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	12% 7% 3 6% 4 4 4 4 6% 7% 43%	137445
	Night	12% 7% 3 7% 4 4 4 3 5% 6% 44%	134865
Transparency	Day	38% 5% 11% 25% 18% 3	141039
	Night	39% 5% 11% 24% 18% 3	139351
Seeing	Day	17% 14% 29% 23% 13% 4	17721
	Night	17% 14% 30% 26% 12% 2	27561

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	12% 10% 4 10% 4 4 4 3 4 6% 38%	4691
	11th to 20th	Day	8% 8% 3 6% 4 4 3 4 4 7% 49%	5170
	21st to end	Day	16% 8% 4 7% 4 4 3 3 5% 5% 40%	5812
February	1st to 10th	Day	15% 11% 3 7% 4 4 4 3 5% 6% 38%	1911
	11th to 20th	Day	14% 9% 3 8% 4 4 4 4 5% 7% 38%	2048
	21st to end	Day	12% 10% 3 6% 4 5% 4 4 6% 6% 40%	1730
March	1st to 10th	Day	15% 12% 3 6% 3 3 3 2 3 5% 46%	4623
	11th to 20th	Day	10% 7% 2 4 3 3 4 3 5% 6% 53%	5090
	21st to end	Day	12% 8% 3 7% 5% 5% 4 4 6% 8% 39%	5906
April	1st to 10th	Day	11% 5% 2 6% 5% 4 4 4 6% 8% 44%	2520
	11th to 20th	Day	15% 8% 3 6% 5% 4 4 3 5% 7% 40%	2494
	21st to end	Day	17% 7% 2 6% 4 5% 4 3 5% 7% 39%	2520
May	1st to 10th	Day	14% 6% 3 7% 5% 5% 5% 4 7% 8% 35%	7139
	11th to 20th	Day	15% 7% 3 7% 4 4 5% 4 6% 8% 37%	7958
	21st to end	Day	18% 8% 3 8% 5% 4 4 4 5% 7% 33%	9047
June	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 7% 8% 44%	2940
	11th to 20th	Day	6% 4 1 5% 5% 5% 5% 4 7% 9% 49%	2871
	21st to end	Day	5% 3 2 4 5% 4 6% 4 9% 10% 48%	2800
July	1st to 10th	Day	11% 4 2 6% 4 4 5% 4 6% 9% 46%	6360
	11th to 20th	Day	5% 4 2 6% 5% 6% 6% 5% 8% 11% 42%	6360
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 6% 8% 10% 41%	6516
August	1st to 10th	Day	6% 3 2 4 4 4 4 4 6% 9% 53%	4145
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 4 6% 8% 46%	3849
	21st to end	Day	6% 5% 2 5% 3 4 5% 3 5% 7% 53%	4312
September	1st to 10th	Day	11% 5% 2 5% 3 4 3 4 5% 9% 49%	2400
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 5% 8% 49%	2360
	21st to end	Day	11% 4 2 5% 4 3 3 4 4 6% 54%	2200
October	1st to 10th	Day	8% 4 2 5% 3 3 3 3 4 6% 59%	2020
	11th to 20th	Day	12% 4 1 5% 2 3 4 2 5% 6% 55%	2000
	21st to end	Day	18% 8% 2 5% 3 3 3 3 3 5% 48%	2189
November	1st to 10th	Day	11% 6% 1 6% 3 3 4 3 4 6% 54%	1852
	11th to 20th	Day	11% 9% 2 5% 4 4 3 3 5% 7% 46%	1890
	21st to end	Day	15% 10% 3 5% 4 3 3 3 5% 6% 43%	1874
December	1st to 10th	Day	10% 9% 2 6% 4 4 3 3 4 6% 51%	2690
	11th to 20th	Day	13% 10% 3 7% 5% 4 3 3 5% 6% 41%	3088
	21st to end	Day	20% 15% 5% 8% 5% 4 5% 3 4 5% 27%	4070
January	1st to 10th	Night	13% 10% 5% 9% 4 4 4 3 5% 5% 38%	8232
	11th to 20th	Night	10% 8% 3 10% 4 5% 4 3 4 5% 44%	7818
	21st to end	Night	17% 9% 3 7% 5% 4 3 3 4 5% 39%	8402
February	1st to 10th	Night	16% 12% 4 8% 5% 3 4 3 4 6% 36%	2707
	11th to 20th	Night	15% 7% 3 9% 4 3 4 3 4 5% 41%	2458
	21st to end	Night	15% 7% 3 7% 4 4 4 4 6% 5% 42%	2076
March	1st to 10th	Night	16% 11% 3 6% 4 4 4 3 4 5% 40%	5493
	11th to 20th	Night	11% 8% 2 6% 3 4 4 3 5% 6% 49%	5090
	21st to end	Night	14% 7% 3 6% 5% 5% 5% 4 5% 7% 39%	5265
April	1st to 10th	Night	10% 5% 2 6% 4 3 5% 4 6% 7% 49%	2100
	11th to 20th	Night	13% 6% 3 6% 4 4 4 4 5% 6% 45%	2075
	21st to end	Night	17% 6% 2 6% 5% 5% 4 3 5% 6% 41%	2100
May	1st to 10th	Night	15% 9% 3 7% 5% 5% 5% 4 6% 7% 36%	5714
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 3 6% 8% 43%	4905
	21st to end	Night	17% 8% 3 8% 6% 4 6% 4 6% 7% 31%	5139
June	1st to 10th	Night	9% 5% 2 5% 4 4 5% 4 7% 8% 47%	1680
	11th to 20th	Night	6% 4 2 4 4 3 3 4 7% 10% 54%	1640
	21st to end	Night	3 3 1 4 3 3 4 4 7% 10% 57%	1600
July	1st to 10th	Night	9% 4 2 6% 3 3 4 3 6% 8% 51%	3618
	11th to 20th	Night	6% 4 2 6% 4 5% 5% 4 7% 8% 49%	3617
	21st to end	Night	5% 4 2 5% 4 5% 5% 5% 7% 11% 46%	4350
August	1st to 10th	Night	6% 3 2 4 2 3 3 3 6% 8% 59%	3011
	11th to 20th	Night	9% 4 2 5% 4 4 4 4 5% 8% 49%	3200
	21st to end	Night	5% 4 1 5% 3 3 4 3 5% 8% 60%	3586
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 4 6% 53%	2000
	11th to 20th	Night	8% 6% 2 4 4 4 4 3 4 8% 53%	2018
	21st to end	Night	11% 4 2 5% 4 3 4 3 5% 6% 54%	2200
October	1st to 10th	Night	6% 3 1 4 3 2 4 3 4 7% 64%	2375
	11th to 20th	Night	13% 5% 2 4 3 3 3 3 4 6% 56%	2400
	21st to end	Night	18% 7% 2 5% 3 2 3 2 4 5% 48%	2650
November	1st to 10th	Night	10% 5% 2 5% 3 3 3 2 4 6% 58%	2666
	11th to 20th	Night	12% 6% 2 4 4 4 4 3 4 6% 51%	2730
	21st to end	Night	16% 9% 2 5% 4 3 3 3 4 5% 46%	2741
December	1st to 10th	Night	13% 8% 3 8% 4 3 3 3 4 5% 47%	4720
	11th to 20th	Night	12% 9% 3 7% 4 4 4 3 4 6% 44%	5339
	21st to end	Night	20% 14% 3 9% 5% 4 4 4 5% 5% 28%	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	48% 4 11% 25% 10% 2	4692
	11th to 20th	Day	36% 4 6% 29% 21% 5%	5170
	21st to end	Day	46% 3 10% 19% 15% 7%	5812
February	1st to 10th	Day	48% 3 13% 22% 13% 1	1911
	11th to 20th	Day	46% 5% 11% 19% 14% 4	2058
	21st to end	Day	44% 4 10% 23% 14% 5%	1730
March	1st to 10th	Day	43% 3 6% 21% 20% 8%	4623
	11th to 20th	Day	31% 4 8% 27% 23% 7%	5090
	21st to end	Day	41% 6% 14% 28% 11% 1	5908
April	1st to 10th	Day	37% 6% 12% 24% 19% 1	2520
	11th to 20th	Day	44% 4 11% 22% 15% 4	2494
	21st to end	Day	44% 6% 11% 24% 13% 1	2520
May	1st to 10th	Day	45% 7% 11% 25% 12% 1	7174
	11th to 20th	Day	45% 5% 10% 21% 17% 1	7962
	21st to end	Day	50% 6% 9% 19% 15% 2	9061
June	1st to 10th	Day	34% 8% 13% 25% 18% 2	2940
	11th to 20th	Day	30% 7% 11% 27% 22% 3	2871
	21st to end	Day	27% 7% 18% 26% 16% 5%	2800
July	1st to 10th	Day	34% 5% 11% 28% 19% 2	6291
	11th to 20th	Day	33% 7% 16% 31% 12% 1	6285
	21st to end	Day	35% 7% 17% 28% 12% 1	6331
August	1st to 10th	Day	26% 6% 15% 34% 19%	4131
	11th to 20th	Day	35% 6% 13% 27% 17% 2	3885
	21st to end	Day	29% 6% 13% 34% 16% 3	4311
September	1st to 10th	Day	33% 4 12% 29% 18% 4	2400
	11th to 20th	Day	32% 6% 10% 27% 23% 2	2360
	21st to end	Day	31% 6% 7% 27% 26% 3	2200
October	1st to 10th	Day	16% 3 5% 21% 45% 9%	3293
	11th to 20th	Day	22% 3 6% 23% 37% 10%	3240
	21st to end	Day	31% 3 6% 28% 28% 4	3515
November	1st to 10th	Day	32% 5% 9% 27% 21% 6%	1852
	11th to 20th	Day	37% 4 9% 24% 20% 6%	1890
	21st to end	Day	43% 4 10% 24% 17% 1	1874
December	1st to 10th	Day	36% 4 9% 34% 17% 1	2690
	11th to 20th	Day	44% 4 9% 25% 17% 1	3085
	21st to end	Day	60% 5% 11% 14% 7% 2	4070
January	1st to 10th	Night	48% 4 12% 24% 10% 1	8233
	11th to 20th	Night	42% 5% 5% 25% 21% 3	7818
	21st to end	Night	48% 4 9% 20% 17% 3	8402
February	1st to 10th	Night	50% 4 9% 22% 12% 2	2707
	11th to 20th	Night	45% 4 10% 21% 16% 3	2459
	21st to end	Night	42% 5% 10% 23% 16% 4	2076
March	1st to 10th	Night	47% 4 6% 19% 19% 5%	5493
	11th to 20th	Night	36% 5% 10% 22% 19% 8%	5090
	21st to end	Night	42% 6% 14% 26% 10% 1	5265
April	1st to 10th	Night	32% 5% 14% 27% 19% 3	2100
	11th to 20th	Night	39% 5% 11% 23% 18% 4	2075
	21st to end	Night	45% 4 9% 24% 15% 2	2100
May	1st to 10th	Night	46% 7% 14% 22% 11% 1	5744
	11th to 20th	Night	40% 5% 14% 25% 15% 2	4906
	21st to end	Night	51% 7% 10% 19% 11% 2	5149
June	1st to 10th	Night	33% 6% 15% 25% 19% 3	1680
	11th to 20th	Night	25% 5% 13% 30% 23% 5%	1640
	21st to end	Night	21% 7% 18% 30% 17% 7%	1600
July	1st to 10th	Night	32% 6% 11% 27% 22% 3	3580
	11th to 20th	Night	32% 7% 15% 30% 14% 2	3572
	21st to end	Night	30% 6% 22% 27% 13% 1	4224
August	1st to 10th	Night	23% 5% 18% 32% 20% 1	3001
	11th to 20th	Night	33% 5% 15% 26% 17% 3	3230
	21st to end	Night	23% 5% 12% 37% 20% 3	3586
September	1st to 10th	Night	33% 4 8% 29% 19% 6%	2000
	11th to 20th	Night	31% 5% 8% 29% 25% 3	2018
	21st to end	Night	31% 4 9% 24% 27% 5%	2200
October	1st to 10th	Night	14% 3 6% 17% 48% 12%	3882
	11th to 20th	Night	22% 3 6% 20% 38% 11%	3899
	21st to end	Night	30% 3 8% 25% 27% 7%	4274
November	1st to 10th	Night	30% 4 11% 28% 22% 6%	2666
	11th to 20th	Night	34% 4 9% 24% 23% 6%	2730
	21st to end	Night	42% 4 8% 25% 19% 2	2741
December	1st to 10th	Night	40% 4 9% 29% 17% 1	4720
	11th to 20th	Night	42% 4 12% 22% 19% 1	5341
	21st to end	Night	57% 6% 12% 17% 7% 1	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	29% 24% 32% 12% 2	330
	11th to 20th	Day	29% 31% 32% 8% 1	330
	21st to end	Day	20% 35% 34% 10% 1	363
February	1st to 10th	Day	25% 28% 34% 10% 2	330
	11th to 20th	Day	34% 29% 27% 8% 1 1	330
	21st to end	Day	33% 26% 32% 8% 1	273
March	1st to 10th	Day	26% 25% 37% 10% 2	330
	11th to 20th	Day	32% 24% 34% 7% 2 1	330
	21st to end	Day	30% 21% 34% 12% 2	505
April	1st to 10th	Day	22% 22% 35% 16% 4	540
	11th to 20th	Day	28% 22% 26% 18% 5% 1	532
	21st to end	Day	22% 19% 37% 17% 4 1	540
May	1st to 10th	Day	18% 22% 37% 17% 5% 1	543
	11th to 20th	Day	21% 14% 32% 21% 9% 3	678
	21st to end	Day	13% 10% 36% 25% 13% 4	844
June	1st to 10th	Day	12% 8% 27% 27% 21% 5%	780
	11th to 20th	Day	8% 6% 29% 35% 17% 4	756
	21st to end	Day	5% 8% 31% 35% 17% 5%	730
July	1st to 10th	Day	12% 4 18% 29% 26% 11%	721
	11th to 20th	Day	6% 4 21% 40% 24% 5%	718
	21st to end	Day	9% 4 19% 36% 26% 6%	794
August	1st to 10th	Day	10% 2 23% 33% 25% 8%	676
	11th to 20th	Day	12% 4 21% 30% 25% 8%	519
	21st to end	Day	10% 4 16% 33% 27% 11%	583
September	1st to 10th	Day	12% 4 20% 32% 25% 7%	530
	11th to 20th	Day	9% 3 17% 35% 28% 9%	530
	21st to end	Day	13% 10% 23% 28% 18% 7%	530
October	1st to 10th	Day	8% 10% 31% 34% 13% 3	350
	11th to 20th	Day	20% 17% 33% 23% 6% 1	330
	21st to end	Day	29% 22% 33% 14% 2	363
November	1st to 10th	Day	15% 16% 42% 19% 5% 3	330
	11th to 20th	Day	22% 24% 31% 16% 7% 1	330
	21st to end	Day	28% 20% 32% 15% 4 1	330
December	1st to 10th	Day	19% 25% 38% 10% 5% 2	330
	11th to 20th	Day	28% 23% 34% 13% 2	330
	21st to end	Day	28% 25% 36% 10% 1	363
January	1st to 10th	Night	21% 24% 35% 17% 3	1050
	11th to 20th	Night	24% 28% 32% 14% 2	1050
	21st to end	Night	21% 23% 37% 17% 1	1155
February	1st to 10th	Night	22% 23% 35% 18% 2	1027
	11th to 20th	Night	23% 24% 35% 16% 1	823
	21st to end	Night	24% 23% 33% 18% 1	692
March	1st to 10th	Night	25% 20% 35% 17% 3	840
	11th to 20th	Night	22% 20% 34% 22% 3	630
	21st to end	Night	24% 18% 32% 23% 4	693
April	1st to 10th	Night	14% 21% 37% 25% 3	630
	11th to 20th	Night	20% 16% 33% 22% 8%	623
	21st to end	Night	21% 13% 36% 22% 7%	630
May	1st to 10th	Night	17% 11% 33% 31% 8% 1	630
	11th to 20th	Night	19% 7% 31% 28% 13% 2	621
	21st to end	Night	11% 6% 30% 34% 16% 3	683
June	1st to 10th	Night	11% 4 25% 35% 23% 1	630
	11th to 20th	Night	8% 3 24% 43% 20% 1	615
	21st to end	Night	4 3 27% 40% 24% 2	600
July	1st to 10th	Night	9% 3 14% 35% 33% 7%	585
	11th to 20th	Night	7% 2 17% 39% 31% 4	582
	21st to end	Night	7% 2 16% 40% 31% 4	657
August	1st to 10th	Night	9% 2 16% 37% 32% 5%	597
	11th to 20th	Night	7% 2 15% 38% 33% 4	594
	21st to end	Night	7% 2 14% 38% 32% 7%	660
September	1st to 10th	Night	13% 4 15% 35% 29% 5%	600
	11th to 20th	Night	10% 3 14% 35% 32% 6%	618
	21st to end	Night	12% 7% 25% 27% 23% 5%	800
October	1st to 10th	Night	7% 5% 29% 33% 21% 5%	800
	11th to 20th	Night	16% 14% 29% 26% 14% 1	800
	21st to end	Night	25% 15% 33% 21% 6%	880
November	1st to 10th	Night	13% 13% 41% 24% 8% 1	820
	11th to 20th	Night	16% 18% 34% 24% 6% 1	840
	21st to end	Night	24% 18% 33% 19% 5%	851
December	1st to 10th	Night	22% 18% 35% 20% 4 1	1050
	11th to 20th	Night	22% 16% 38% 20% 4	1050
	21st to end	Night	25% 22% 35% 16% 3	1155

Page generated at 2026-06-13 01:31:43. Version ac07

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