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 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	12% 7% 3 6% 4 4 4 4 6% 7% 44%	108573
	Night	13% 7% 3 6% 4 4 4 3 5% 6% 45%	110206
Transparency	Day	37% 5% 11% 25% 18% 3	112206
	Night	38% 5% 11% 24% 19% 3	114714
Seeing	Day	17% 14% 29% 24% 13% 4	15890
	Night	17% 14% 30% 26% 12% 2	25860

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	14% 10% 5% 11% 4 4 4 3 4 5% 35%	3617
	11th to 20th	Day	10% 8% 3 7% 4 4 3 4 4 7% 47%	3968
	21st to end	Day	17% 9% 4 6% 4 3 3 3 5% 5% 39%	4488
February	1st to 10th	Day	16% 11% 3 7% 4 4 4 3 5% 6% 38%	1820
	11th to 20th	Day	14% 10% 3 8% 4 4 4 4 5% 7% 37%	1948
	21st to end	Day	13% 10% 3 6% 4 5% 4 4 6% 6% 38%	1570
March	1st to 10th	Day	18% 12% 3 6% 4 3 3 3 3 5% 40%	3148
	11th to 20th	Day	13% 7% 2 4 3 3 3 3 5% 5% 51%	3480
	21st to end	Day	14% 8% 3 6% 5% 5% 4 4 6% 7% 38%	4032
April	1st to 10th	Day	10% 5% 2 6% 5% 4 4 4 6% 8% 45%	2280
	11th to 20th	Day	15% 8% 3 6% 5% 4 4 3 4 7% 41%	2254
	21st to end	Day	18% 7% 2 6% 4 4 4 3 5% 6% 39%	2280
May	1st to 10th	Day	13% 6% 2 7% 5% 6% 5% 5% 7% 9% 34%	3829
	11th to 20th	Day	18% 8% 2 6% 3 4 4 3 5% 8% 38%	4259
	21st to end	Day	10% 7% 3 6% 5% 5% 4 4 6% 7% 43%	4824
June	1st to 10th	Day	10% 4 2 6% 4 4 5% 5% 7% 8% 45%	2660
	11th to 20th	Day	6% 4 1 5% 5% 4 5% 4 7% 9% 51%	2660
	21st to end	Day	5% 3 2 4 4 4 6% 5% 9% 10% 48%	2660
July	1st to 10th	Day	13% 4 2 5% 5% 5% 5% 4 7% 10% 41%	4440
	11th to 20th	Day	4 3 1 5% 4 5% 6% 4 7% 11% 49%	4440
	21st to end	Day	7% 6% 3 7% 6% 6% 7% 6% 8% 9% 37%	4531
August	1st to 10th	Day	6% 3 2 4 4 4 5% 4 6% 9% 53%	4018
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 46%	3729
	21st to end	Day	7% 5% 2 5% 3 4 5% 3 5% 7% 53%	4180
September	1st to 10th	Day	11% 5% 2 5% 3 4 3 3 5% 9% 49%	2280
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 5% 8% 48%	2242
	21st to end	Day	11% 4 1 5% 4 3 3 4 4 6% 54%	2090
October	1st to 10th	Day	8% 4 2 5% 3 3 3 3 4 6% 59%	1919
	11th to 20th	Day	12% 4 2 6% 2 4 3 2 5% 6% 54%	1900
	21st to end	Day	17% 8% 2 5% 3 3 3 3 3 5% 48%	2080
November	1st to 10th	Day	11% 5% 1 6% 3 3 4 3 4 6% 54%	1762
	11th to 20th	Day	11% 9% 2 5% 4 3 3 3 5% 7% 47%	1800
	21st to end	Day	15% 9% 3 5% 4 3 4 3 5% 5% 43%	1785
December	1st to 10th	Day	10% 9% 2 5% 4 4 3 3 4 5% 51%	2610
	11th to 20th	Day	13% 10% 3 7% 5% 4 3 3 5% 6% 40%	3008
	21st to end	Day	20% 15% 5% 8% 5% 4 4 3 4 5% 26%	3982
January	1st to 10th	Night	15% 11% 5% 10% 4 4 4 3 5% 5% 34%	6348
	11th to 20th	Night	12% 9% 3 11% 4 5% 5% 3 4 5% 39%	6010
	21st to end	Night	18% 9% 3 6% 4 4 3 3 4 5% 40%	6490
February	1st to 10th	Night	17% 13% 4 8% 5% 3 4 3 4 6% 35%	2578
	11th to 20th	Night	15% 8% 3 10% 4 3 4 3 4 5% 41%	2338
	21st to end	Night	16% 8% 3 7% 4 4 4 4 5% 5% 40%	1885
March	1st to 10th	Night	21% 10% 2 5% 3 4 3 2 4 4 41%	3733
	11th to 20th	Night	12% 6% 2 6% 3 3 3 3 4 6% 50%	3480
	21st to end	Night	14% 7% 3 6% 5% 5% 5% 4 6% 7% 38%	3599
April	1st to 10th	Night	9% 5% 2 6% 4 3 5% 4 5% 7% 50%	1900
	11th to 20th	Night	13% 6% 3 6% 4 4 4 4 5% 6% 45%	1875
	21st to end	Night	18% 7% 2 6% 5% 5% 4 3 5% 5% 41%	1900
May	1st to 10th	Night	17% 8% 2 5% 4 4 4 4 5% 8% 40%	3066
	11th to 20th	Night	16% 7% 2 5% 3 3 4 3 5% 7% 46%	2639
	21st to end	Night	9% 6% 3 7% 6% 5% 6% 5% 6% 9% 40%	2743
June	1st to 10th	Night	9% 5% 2 5% 3 4 4 4 7% 8% 48%	1520
	11th to 20th	Night	5% 3 2 4 4 3 3 4 7% 10% 56%	1520
	21st to end	Night	3 3 1 4 3 3 4 4 7% 10% 56%	1520
July	1st to 10th	Night	11% 4 2 4 3 3 4 3 6% 8% 51%	2530
	11th to 20th	Night	6% 3 2 4 4 4 4 3 6% 7% 56%	2530
	21st to end	Night	6% 5% 3 6% 5% 6% 6% 4 7% 9% 42%	3027
August	1st to 10th	Night	6% 3 2 4 3 3 3 3 6% 8% 60%	2918
	11th to 20th	Night	10% 4 2 6% 4 4 4 4 5% 8% 49%	3100
	21st to end	Night	5% 4 1 5% 3 3 4 3 5% 8% 59%	3476
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 4 6% 53%	1900
	11th to 20th	Night	9% 6% 2 4 4 4 4 3 4 8% 52%	1917
	21st to end	Night	10% 4 2 5% 3 2 4 3 5% 6% 54%	2090
October	1st to 10th	Night	6% 3 1 4 3 2 4 3 4 7% 63%	2256
	11th to 20th	Night	13% 5% 2 4 3 3 3 3 4 5% 56%	2280
	21st to end	Night	17% 7% 2 6% 3 2 3 2 5% 5% 48%	2517
November	1st to 10th	Night	10% 5% 2 5% 3 3 3 2 4 6% 58%	2536
	11th to 20th	Night	12% 6% 2 5% 4 4 4 3 5% 7% 51%	2600
	21st to end	Night	16% 9% 2 5% 4 3 3 3 4 5% 47%	2610
December	1st to 10th	Night	13% 8% 3 7% 4 3 3 3 4 5% 48%	4580
	11th to 20th	Night	12% 9% 3 7% 4 4 4 3 4 6% 44%	5199
	21st to end	Night	20% 14% 3 9% 5% 4 4 4 5% 5% 27%	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	50% 5% 10% 22% 11% 2	3618
	11th to 20th	Day	38% 4 7% 27% 19% 5%	3968
	21st to end	Day	46% 4 10% 16% 17% 7%	4488
February	1st to 10th	Day	48% 3 13% 21% 13% 1	1820
	11th to 20th	Day	47% 5% 12% 18% 14% 5%	1958
	21st to end	Day	45% 4 10% 22% 13% 5%	1570
March	1st to 10th	Day	48% 4 7% 19% 14% 7%	3148
	11th to 20th	Day	35% 5% 9% 28% 17% 6%	3480
	21st to end	Day	43% 7% 16% 21% 13% 1	4032
April	1st to 10th	Day	36% 6% 12% 25% 20% 1	2280
	11th to 20th	Day	43% 4 10% 23% 16% 4	2254
	21st to end	Day	45% 6% 11% 23% 13% 1	2280
May	1st to 10th	Day	42% 10% 14% 22% 11% 1	3864
	11th to 20th	Day	44% 6% 11% 25% 12% 1	4263
	21st to end	Day	38% 7% 11% 22% 22% 1	4837
June	1st to 10th	Day	33% 8% 14% 25% 18% 2	2660
	11th to 20th	Day	28% 7% 12% 28% 22% 3	2660
	21st to end	Day	27% 7% 18% 26% 16% 5%	2660
July	1st to 10th	Day	37% 6% 13% 28% 13% 3	4371
	11th to 20th	Day	27% 6% 14% 34% 16% 2	4365
	21st to end	Day	40% 8% 16% 26% 10% 1	4388
August	1st to 10th	Day	26% 6% 15% 33% 19%	4004
	11th to 20th	Day	36% 6% 13% 26% 17% 2	3765
	21st to end	Day	29% 5% 13% 35% 15% 3	4179
September	1st to 10th	Day	33% 5% 12% 29% 18% 4	2280
	11th to 20th	Day	34% 6% 10% 26% 23% 2	2242
	21st to end	Day	31% 6% 8% 28% 25% 3	2090
October	1st to 10th	Day	16% 3 5% 21% 45% 9%	3192
	11th to 20th	Day	22% 3 6% 23% 38% 10%	3140
	21st to end	Day	30% 3 6% 28% 29% 4	3406
November	1st to 10th	Day	32% 5% 10% 26% 22% 6%	1762
	11th to 20th	Day	36% 5% 8% 24% 21% 7%	1800
	21st to end	Day	43% 5% 10% 24% 17% 1	1785
December	1st to 10th	Day	36% 4 8% 34% 17% 1	2610
	11th to 20th	Day	44% 4 9% 24% 17% 1	3005
	21st to end	Day	60% 5% 11% 14% 7% 2	3982
January	1st to 10th	Night	52% 5% 9% 22% 12% 1	6348
	11th to 20th	Night	46% 6% 6% 23% 17% 2	6010
	21st to end	Night	47% 4 7% 21% 18% 3	6490
February	1st to 10th	Night	52% 4 9% 21% 12% 2	2578
	11th to 20th	Night	46% 4 10% 20% 17% 3	2339
	21st to end	Night	45% 5% 10% 21% 15% 5%	1885
March	1st to 10th	Night	48% 4 8% 20% 16% 4	3733
	11th to 20th	Night	35% 6% 12% 23% 19% 5%	3480
	21st to end	Night	42% 8% 15% 27% 7% 1	3599
April	1st to 10th	Night	32% 5% 13% 27% 19% 3	1900
	11th to 20th	Night	39% 5% 10% 22% 19% 4	1875
	21st to end	Night	45% 4 9% 24% 15% 2	1900
May	1st to 10th	Night	41% 8% 16% 21% 12% 1	3096
	11th to 20th	Night	38% 6% 15% 24% 16% 1	2640
	21st to end	Night	38% 8% 12% 23% 17% 1	2751
June	1st to 10th	Night	32% 6% 15% 25% 19% 3	1520
	11th to 20th	Night	23% 5% 13% 31% 24% 5%	1520
	21st to end	Night	21% 7% 18% 29% 17% 8%	1520
July	1st to 10th	Night	33% 5% 13% 30% 15% 4	2490
	11th to 20th	Night	26% 6% 11% 35% 19% 3	2482
	21st to end	Night	35% 7% 19% 25% 13% 2	2931
August	1st to 10th	Night	23% 5% 18% 32% 21% 1	2908
	11th to 20th	Night	34% 5% 15% 25% 18% 3	3130
	21st to end	Night	23% 5% 12% 38% 19% 3	3476
September	1st to 10th	Night	33% 4 8% 29% 19% 7%	1900
	11th to 20th	Night	31% 5% 8% 28% 24% 3	1917
	21st to end	Night	31% 4 9% 25% 26% 5%	2090
October	1st to 10th	Night	13% 3 7% 17% 48% 12%	3763
	11th to 20th	Night	23% 3 6% 20% 38% 11%	3779
	21st to end	Night	29% 3 8% 26% 27% 7%	4141
November	1st to 10th	Night	30% 4 11% 27% 23% 6%	2536
	11th to 20th	Night	34% 4 8% 24% 24% 6%	2600
	21st to end	Night	41% 4 8% 25% 20% 2	2610
December	1st to 10th	Night	39% 4 9% 29% 17% 1	4580
	11th to 20th	Night	42% 4 12% 22% 19% 1	5201
	21st to end	Night	58% 6% 12% 16% 7% 1	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	29% 24% 31% 12% 2	300
	11th to 20th	Day	28% 31% 32% 8% 1	300
	21st to end	Day	19% 36% 34% 10% 1	330
February	1st to 10th	Day	26% 29% 34% 10% 1	300
	11th to 20th	Day	34% 29% 27% 9% 1 1	300
	21st to end	Day	32% 28% 32% 7% 1	225
March	1st to 10th	Day	24% 24% 40% 11% 1	270
	11th to 20th	Day	31% 24% 34% 8% 2	270
	21st to end	Day	31% 20% 33% 13% 2	425
April	1st to 10th	Day	21% 22% 35% 18% 5%	460
	11th to 20th	Day	27% 21% 26% 19% 6% 1	452
	21st to end	Day	23% 20% 35% 16% 5% 1	460
May	1st to 10th	Day	17% 22% 35% 19% 6% 1	463
	11th to 20th	Day	20% 12% 32% 22% 10% 3	587
	21st to end	Day	10% 9% 37% 26% 14% 4	734
June	1st to 10th	Day	11% 8% 24% 29% 23% 5%	680
	11th to 20th	Day	6% 5% 30% 35% 19% 5%	680
	21st to end	Day	5% 8% 32% 34% 17% 5%	680
July	1st to 10th	Day	12% 4 18% 28% 26% 11%	671
	11th to 20th	Day	5% 4 21% 39% 25% 6%	668
	21st to end	Day	9% 4 20% 35% 26% 6%	739
August	1st to 10th	Day	10% 2 22% 32% 26% 8%	629
	11th to 20th	Day	12% 4 23% 30% 24% 8%	479
	21st to end	Day	10% 4 16% 32% 27% 12%	539
September	1st to 10th	Day	13% 4 19% 33% 24% 7%	490
	11th to 20th	Day	10% 3 18% 33% 27% 9%	490
	21st to end	Day	13% 10% 23% 28% 18% 7%	490
October	1st to 10th	Day	9% 11% 30% 34% 14% 3	319
	11th to 20th	Day	20% 18% 33% 22% 6% 1	300
	21st to end	Day	27% 22% 33% 15% 2	330
November	1st to 10th	Day	14% 16% 42% 19% 6% 3	300
	11th to 20th	Day	22% 24% 29% 16% 8% 1	300
	21st to end	Day	26% 20% 34% 15% 4 1	300
December	1st to 10th	Day	19% 24% 38% 11% 6% 2	300
	11th to 20th	Day	28% 21% 34% 14% 2	300
	21st to end	Day	29% 26% 33% 11% 2	330
January	1st to 10th	Night	21% 24% 35% 17% 3	1000
	11th to 20th	Night	24% 28% 32% 15% 3	1000
	21st to end	Night	21% 23% 38% 17% 1	1100
February	1st to 10th	Night	24% 24% 34% 17% 2	978
	11th to 20th	Night	23% 25% 35% 16% 2	783
	21st to end	Night	25% 23% 33% 18% 1	629
March	1st to 10th	Night	25% 20% 36% 17% 3	760
	11th to 20th	Night	21% 19% 34% 23% 3	570
	21st to end	Night	24% 16% 33% 23% 4	627
April	1st to 10th	Night	14% 21% 36% 26% 4	570
	11th to 20th	Night	20% 16% 31% 24% 9%	563
	21st to end	Night	22% 13% 36% 22% 7%	570
May	1st to 10th	Night	16% 11% 34% 31% 8% 1	570
	11th to 20th	Night	18% 6% 31% 28% 14% 2	561
	21st to end	Night	9% 5% 30% 35% 17% 3	617
June	1st to 10th	Night	11% 4 24% 36% 24% 1	570
	11th to 20th	Night	6% 3 24% 44% 21% 1	570
	21st to end	Night	4 3 28% 40% 24% 2	570
July	1st to 10th	Night	9% 3 14% 34% 33% 7%	555
	11th to 20th	Night	6% 2 17% 39% 31% 4	552
	21st to end	Night	8% 2 17% 39% 31% 4	624
August	1st to 10th	Night	8% 2 16% 36% 33% 5%	567
	11th to 20th	Night	7% 2 16% 38% 32% 4	564
	21st to end	Night	7% 2 14% 37% 33% 7%	627
September	1st to 10th	Night	13% 3 15% 34% 29% 5%	570
	11th to 20th	Night	11% 3 14% 36% 31% 6%	587
	21st to end	Night	12% 7% 25% 27% 23% 6%	760
October	1st to 10th	Night	7% 5% 30% 32% 21% 5%	760
	11th to 20th	Night	17% 14% 29% 26% 13% 1	760
	21st to end	Night	23% 15% 34% 22% 6%	836
November	1st to 10th	Night	13% 12% 42% 24% 9% 1	780
	11th to 20th	Night	17% 18% 33% 25% 7% 1	800
	21st to end	Night	23% 19% 33% 19% 6%	810
December	1st to 10th	Night	22% 18% 35% 20% 4 1	1000
	11th to 20th	Night	23% 15% 38% 21% 4	1000
	21st to end	Night	25% 22% 35% 16% 3	1100

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

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