Warren Dunes State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Warren Dunes State Park clear sky chart from 2005-11-06 to 2026-09-14.

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	13% 10% 4 9% 5% 4 4 3 5% 7% 35%	148786
	Night	14% 12% 5% 10% 5% 4 4 3 5% 6% 31%	142601
Transparency	Day	49% 4 11% 23% 13% 1	152325
	Night	54% 3 10% 20% 12% 1	147139
Seeing	Day	19% 15% 29% 22% 11% 4	18355
	Night	21% 12% 27% 27% 11% 1	28106

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% 21% 10% 22% 5% 3 3 3 3 4 12%	4691
	11th to 20th	Day	10% 16% 10% 17% 11% 10% 8% 2 2 3 9%	4710
	21st to end	Day	15% 17% 5% 15% 8% 7% 5% 4 3 4 18%	5156
February	1st to 10th	Day	14% 16% 6% 13% 8% 5% 4 3 5% 5% 19%	1995
	11th to 20th	Day	14% 12% 6% 16% 7% 5% 4 3 5% 4 24%	2048
	21st to end	Day	15% 15% 7% 11% 6% 4 4 3 4 6% 24%	1730
March	1st to 10th	Day	17% 12% 6% 10% 5% 3 3 3 4 5% 33%	4580
	11th to 20th	Day	9% 9% 8% 8% 4 4 4 3 6% 8% 37%	4850
	21st to end	Day	17% 16% 6% 11% 6% 4 4 3 4 5% 23%	5945
April	1st to 10th	Day	17% 13% 4 7% 4 4 4 3 5% 6% 33%	2520
	11th to 20th	Day	14% 11% 2 7% 4 4 4 4 4 7% 38%	2494
	21st to end	Day	17% 10% 2 7% 4 4 4 3 6% 8% 35%	2719
May	1st to 10th	Day	17% 8% 3 6% 4 4 5% 4 5% 7% 38%	7616
	11th to 20th	Day	13% 7% 3 7% 5% 4 5% 4 6% 7% 40%	7681
	21st to end	Day	14% 6% 2 6% 4 3 4 3 5% 8% 44%	9047
June	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 6% 7% 46%	2940
	11th to 20th	Day	9% 5% 2 5% 5% 4 5% 4 6% 8% 47%	2940
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 7% 8% 45%	2940
July	1st to 10th	Day	10% 6% 2 6% 4 5% 5% 4 6% 9% 43%	8280
	11th to 20th	Day	8% 4 2 5% 4 4 4 4 6% 10% 49%	8280
	21st to end	Day	9% 6% 2 6% 4 4 5% 4 6% 9% 44%	8990
August	1st to 10th	Day	13% 6% 2 5% 4 4 4 3 6% 8% 44%	6116
	11th to 20th	Day	15% 7% 3 7% 4 4 4 4 5% 7% 40%	5788
	21st to end	Day	7% 4 2 6% 4 4 5% 4 6% 9% 49%	6080
September	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 6% 8% 48%	2520
	11th to 20th	Day	12% 5% 1 5% 3 4 4 4 6% 8% 49%	2237
	21st to end	Day	14% 7% 3 6% 4 3 5% 4 6% 7% 41%	2200
October	1st to 10th	Day	15% 7% 2 6% 5% 4 4 4 4 6% 45%	2200
	11th to 20th	Day	22% 8% 3 6% 4 4 4 3 5% 7% 33%	1963
	21st to end	Day	24% 11% 3 8% 4 4 5% 3 5% 7% 26%	1980
November	1st to 10th	Day	15% 12% 3 7% 4 3 4 4 6% 6% 37%	1852
	11th to 20th	Day	17% 20% 4 10% 5% 3 4 3 4 6% 25%	1890
	21st to end	Day	20% 18% 7% 10% 5% 4 4 2 3 4 23%	1890
December	1st to 10th	Day	11% 20% 12% 17% 4 3 3 2 4 5% 20%	2760
	11th to 20th	Day	15% 21% 10% 14% 7% 4 4 3 4 5% 14%	3088
	21st to end	Day	23% 21% 8% 15% 6% 4 4 2 3 4 10%	4070
January	1st to 10th	Night	13% 21% 10% 22% 5% 4 4 3 3 4 12%	8232
	11th to 20th	Night	11% 20% 9% 22% 8% 8% 6% 2 3 3 9%	8280
	21st to end	Night	16% 17% 8% 15% 8% 6% 5% 2 3 4 16%	9058
February	1st to 10th	Night	16% 16% 5% 12% 9% 5% 3 3 4 5% 22%	2619
	11th to 20th	Night	15% 14% 4 13% 7% 5% 5% 3 5% 5% 24%	2458
	21st to end	Night	18% 15% 7% 12% 5% 3 4 2 4 4 27%	2076
March	1st to 10th	Night	15% 12% 6% 10% 4 4 3 3 4 5% 33%	5493
	11th to 20th	Night	12% 9% 4 7% 4 4 5% 4 4 6% 41%	5329
	21st to end	Night	18% 13% 6% 9% 4 4 4 3 5% 5% 29%	5270
April	1st to 10th	Night	15% 12% 3 7% 5% 5% 4 4 5% 7% 34%	2100
	11th to 20th	Night	19% 9% 2 7% 4 4 4 4 6% 6% 36%	2075
	21st to end	Night	17% 8% 3 7% 4 5% 4 4 5% 6% 37%	1899
May	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 5% 7% 37%	5237
	11th to 20th	Night	13% 6% 2 6% 4 4 4 3 6% 8% 44%	5179
	21st to end	Night	16% 7% 2 7% 4 4 3 3 5% 7% 42%	5139
June	1st to 10th	Night	10% 5% 2 5% 4 3 4 4 6% 9% 48%	1680
	11th to 20th	Night	10% 6% 3 5% 5% 5% 4 4 6% 8% 44%	1680
	21st to end	Night	9% 5% 2 6% 5% 5% 4 5% 7% 9% 42%	1680
July	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 6% 8% 45%	4708
	11th to 20th	Night	7% 4 2 5% 4 4 5% 4 6% 8% 52%	4707
	21st to end	Night	9% 6% 2 6% 4 4 5% 4 7% 8% 45%	5117
August	1st to 10th	Night	14% 6% 2 5% 4 4 4 4 6% 8% 43%	4023
	11th to 20th	Night	13% 7% 2 7% 5% 5% 5% 4 5% 7% 40%	4254
	21st to end	Night	8% 5% 2 6% 4 4 4 3 6% 8% 49%	5046
September	1st to 10th	Night	11% 5% 2 6% 4 4 3 4 5% 7% 49%	2100
	11th to 20th	Night	11% 5% 2 4 3 3 2 3 5% 9% 54%	2208
	21st to end	Night	13% 6% 2 6% 4 4 4 3 5% 7% 43%	2200
October	1st to 10th	Night	15% 6% 2 5% 4 4 4 3 5% 7% 47%	2200
	11th to 20th	Night	22% 8% 3 7% 4 3 3 3 4 6% 36%	2433
	21st to end	Night	25% 10% 3 8% 4 3 3 3 4 5% 33%	2860
November	1st to 10th	Night	17% 14% 3 6% 4 3 4 2 5% 5% 37%	2666
	11th to 20th	Night	15% 20% 5% 10% 4 4 4 3 5% 5% 26%	2730
	21st to end	Night	20% 21% 6% 8% 4 4 3 3 3 5% 24%	2730
December	1st to 10th	Night	12% 19% 9% 17% 6% 5% 5% 3 4 5% 16%	4646
	11th to 20th	Night	15% 23% 11% 15% 6% 4 3 2 4 4 12%	5339
	21st to end	Night	23% 22% 7% 13% 5% 4 4 3 4 4 10%	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	78% 2 9% 9% 2	4692
	11th to 20th	Day	83% 2 6% 7% 2	4710
	21st to end	Day	73% 2 9% 13% 3	5156
February	1st to 10th	Day	68% 3 10% 12% 5% 1	1995
	11th to 20th	Day	64% 3 9% 16% 7%	2058
	21st to end	Day	63% 3 10% 14% 8% 1	1730
March	1st to 10th	Day	56% 2 10% 22% 9%	4580
	11th to 20th	Day	46% 2 12% 31% 8% 1	4850
	21st to end	Day	65% 2 9% 16% 6% 1	5947
April	1st to 10th	Day	53% 3 9% 22% 12%	2520
	11th to 20th	Day	47% 3 10% 23% 14% 3	2494
	21st to end	Day	48% 3 11% 22% 13% 2	2719
May	1st to 10th	Day	46% 3 10% 26% 14% 1	7651
	11th to 20th	Day	44% 4 12% 25% 15% 1	7685
	21st to end	Day	40% 3 10% 25% 19% 4	9061
June	1st to 10th	Day	38% 4 10% 26% 20% 2	2940
	11th to 20th	Day	35% 4 11% 26% 20% 3	2940
	21st to end	Day	36% 5% 15% 25% 16% 3	2940
July	1st to 10th	Day	38% 5% 13% 26% 18% 2	8211
	11th to 20th	Day	30% 6% 13% 33% 18% 1	8205
	21st to end	Day	36% 6% 13% 25% 19% 2	8794
August	1st to 10th	Day	39% 4 12% 27% 17% 1	6101
	11th to 20th	Day	43% 5% 12% 27% 12% 1	5827
	21st to end	Day	32% 5% 13% 32% 16% 2	6079
September	1st to 10th	Day	35% 5% 13% 27% 17% 3	2520
	11th to 20th	Day	33% 4 11% 31% 20% 2	2237
	21st to end	Day	41% 5% 9% 27% 17% 1	2200
October	1st to 10th	Day	30% 3 8% 36% 22% 1	3590
	11th to 20th	Day	40% 4 10% 22% 23%	3166
	21st to end	Day	51% 2 9% 24% 11% 2	3180
November	1st to 10th	Day	48% 3 13% 21% 13% 1	1852
	11th to 20th	Day	63% 2 9% 18% 7% 1	1890
	21st to end	Day	68% 2 9% 17% 4	1890
December	1st to 10th	Day	69% 2 15% 11% 3	2760
	11th to 20th	Day	74% 3 11% 10% 1	3085
	21st to end	Day	81% 2 7% 9% 2	4070
January	1st to 10th	Night	78% 2 6% 11% 2	8233
	11th to 20th	Night	84% 1 8% 6% 1	8280
	21st to end	Night	74% 2 11% 9% 3	9058
February	1st to 10th	Night	66% 3 9% 14% 7% 1	2619
	11th to 20th	Night	63% 2 10% 18% 7% 1	2459
	21st to end	Night	63% 2 9% 18% 6% 2	2076
March	1st to 10th	Night	55% 2 12% 24% 7% 1	5493
	11th to 20th	Night	46% 2 11% 29% 11% 2	5329
	21st to end	Night	58% 2 10% 20% 10% 1	5270
April	1st to 10th	Night	51% 4 11% 21% 13% 1	2100
	11th to 20th	Night	49% 3 8% 21% 17% 3	2075
	21st to end	Night	48% 4 10% 22% 14% 2	1899
May	1st to 10th	Night	48% 3 10% 24% 13% 3	5264
	11th to 20th	Night	40% 3 13% 22% 20% 2	5180
	21st to end	Night	43% 3 9% 19% 23% 4	5149
June	1st to 10th	Night	34% 4 10% 30% 19% 3	1680
	11th to 20th	Night	38% 4 12% 23% 20% 2	1680
	21st to end	Night	37% 4 17% 25% 15% 2	1680
July	1st to 10th	Night	36% 4 11% 29% 15% 4	4670
	11th to 20th	Night	30% 5% 11% 25% 27% 2	4662
	21st to end	Night	35% 5% 13% 24% 20% 3	5002
August	1st to 10th	Night	38% 5% 12% 27% 18%	4014
	11th to 20th	Night	43% 6% 11% 25% 15% 1	4281
	21st to end	Night	33% 4 9% 34% 17% 2	5046
September	1st to 10th	Night	36% 4 12% 26% 18% 5%	2100
	11th to 20th	Night	30% 3 8% 31% 26% 3	2208
	21st to end	Night	41% 3 10% 27% 18% 2	2200
October	1st to 10th	Night	28% 3 9% 33% 26% 2	3590
	11th to 20th	Night	45% 2 7% 21% 23% 1	3969
	21st to end	Night	45% 2 8% 27% 17% 1	4610
November	1st to 10th	Night	51% 3 8% 22% 14% 2	2666
	11th to 20th	Night	61% 3 10% 17% 8% 1	2730
	21st to end	Night	66% 2 10% 17% 5%	2730
December	1st to 10th	Night	71% 3 12% 11% 3	4646
	11th to 20th	Night	79% 2 9% 8% 2	5341
	21st to end	Night	79% 2 9% 8% 2	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	22% 21% 36% 15% 5% 1	330
	11th to 20th	Day	24% 25% 35% 11% 4 1	330
	21st to end	Day	26% 24% 31% 16% 2	363
February	1st to 10th	Day	28% 22% 33% 12% 4 1	330
	11th to 20th	Day	25% 29% 32% 12% 1	330
	21st to end	Day	29% 30% 32% 7% 2	273
March	1st to 10th	Day	24% 27% 37% 10% 2	330
	11th to 20th	Day	27% 21% 30% 16% 5% 1	430
	21st to end	Day	30% 19% 31% 14% 5% 1	594
April	1st to 10th	Day	28% 21% 29% 18% 3 1	540
	11th to 20th	Day	23% 26% 28% 15% 7% 2	532
	21st to end	Day	25% 17% 31% 18% 6% 2	540
May	1st to 10th	Day	24% 17% 31% 19% 7% 2	543
	11th to 20th	Day	22% 16% 29% 22% 9% 3	583
	21st to end	Day	14% 13% 32% 25% 13% 4	844
June	1st to 10th	Day	12% 13% 32% 29% 12% 4	780
	11th to 20th	Day	13% 11% 30% 31% 13% 3	780
	21st to end	Day	13% 10% 33% 28% 12% 4	780
July	1st to 10th	Day	9% 7% 27% 28% 20% 9%	771
	11th to 20th	Day	11% 6% 30% 29% 18% 7%	768
	21st to end	Day	8% 6% 27% 34% 19% 5%	849
August	1st to 10th	Day	9% 4 22% 29% 25% 11%	617
	11th to 20th	Day	12% 7% 24% 26% 23% 8%	559
	21st to end	Day	9% 5% 22% 33% 22% 8%	627
September	1st to 10th	Day	15% 6% 23% 29% 21% 6%	570
	11th to 20th	Day	9% 7% 18% 29% 27% 11%	542
	21st to end	Day	18% 12% 20% 25% 16% 8%	530
October	1st to 10th	Day	17% 10% 27% 26% 18% 2	530
	11th to 20th	Day	24% 17% 30% 22% 6%	384
	21st to end	Day	34% 14% 36% 14% 1 1	363
November	1st to 10th	Day	18% 19% 38% 18% 5% 2	330
	11th to 20th	Day	29% 25% 26% 14% 5%	330
	21st to end	Day	34% 20% 33% 11% 1	330
December	1st to 10th	Day	24% 30% 29% 12% 5% 1	330
	11th to 20th	Day	23% 31% 32% 12% 2 1	330
	21st to end	Day	25% 29% 33% 12% 1	363
January	1st to 10th	Night	25% 17% 36% 18% 4	1050
	11th to 20th	Night	26% 18% 35% 17% 3	1050
	21st to end	Night	24% 17% 35% 21% 3	1155
February	1st to 10th	Night	26% 16% 33% 22% 3	897
	11th to 20th	Night	22% 19% 33% 21% 4	823
	21st to end	Night	27% 18% 35% 17% 3	692
March	1st to 10th	Night	23% 17% 32% 21% 6% 1	840
	11th to 20th	Night	22% 13% 34% 25% 6%	840
	21st to end	Night	25% 13% 27% 28% 6%	787
April	1st to 10th	Night	21% 16% 33% 24% 6% 1	630
	11th to 20th	Night	24% 13% 30% 25% 7% 1	623
	21st to end	Night	21% 12% 30% 27% 9% 1	630
May	1st to 10th	Night	21% 7% 30% 30% 10% 1	630
	11th to 20th	Night	19% 8% 24% 35% 13% 1	621
	21st to end	Night	14% 4 23% 39% 19% 1	683
June	1st to 10th	Night	12% 5% 24% 41% 17% 1	630
	11th to 20th	Night	14% 4 29% 37% 15% 1	630
	21st to end	Night	11% 6% 23% 39% 20% 1	630
July	1st to 10th	Night	9% 3 16% 40% 28% 4	615
	11th to 20th	Night	9% 4 18% 37% 28% 4	612
	21st to end	Night	8% 3 15% 43% 29% 2	690
August	1st to 10th	Night	9% 2 13% 44% 29% 3	627
	11th to 20th	Night	11% 4 14% 38% 29% 5%	624
	21st to end	Night	10% 3 14% 41% 28% 3	693
September	1st to 10th	Night	12% 5% 17% 37% 23% 5%	630
	11th to 20th	Night	12% 4 15% 38% 28% 4	787
	21st to end	Night	15% 7% 23% 29% 22% 3	800
October	1st to 10th	Night	18% 6% 25% 31% 19% 1	800
	11th to 20th	Night	26% 15% 22% 28% 7% 1	800
	21st to end	Night	29% 15% 27% 23% 5%	880
November	1st to 10th	Night	26% 12% 31% 21% 9% 1	820
	11th to 20th	Night	27% 19% 30% 20% 4	840
	21st to end	Night	32% 14% 29% 20% 4	840
December	1st to 10th	Night	29% 20% 31% 16% 4	1002
	11th to 20th	Night	27% 16% 35% 18% 3	1050
	21st to end	Night	32% 17% 32% 17% 2	1155

Page generated at 2026-09-11 04:11:58. Version ac07

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