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 2025-04-26.

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	14% 11% 4 9% 5% 4 4 3 5% 7% 35%	113359
	Night	15% 13% 5% 10% 5% 4 4 3 5% 6% 30%	115456
Transparency	Day	50% 3 11% 22% 12% 1	116945
	Night	55% 3 10% 19% 11% 1	120013
Seeing	Day	19% 15% 29% 22% 12% 4	16335
	Night	21% 12% 27% 27% 12% 1	26331

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% 21% 10% 21% 5% 4 3 2 3 5% 14%	3617
	11th to 20th	Day	12% 18% 9% 18% 11% 8% 10% 2 2 3 9%	3620
	21st to end	Day	19% 19% 6% 13% 5% 3 4 4 3 4 20%	3982
February	1st to 10th	Day	15% 16% 6% 12% 8% 5% 4 3 5% 5% 19%	1900
	11th to 20th	Day	15% 12% 6% 16% 7% 5% 4 3 5% 4 23%	1948
	21st to end	Day	15% 15% 7% 11% 6% 4 4 3 4 6% 25%	1650
March	1st to 10th	Day	17% 12% 6% 10% 5% 3 3 3 4 5% 33%	4480
	11th to 20th	Day	9% 9% 8% 8% 4 4 4 3 6% 9% 37%	4745
	21st to end	Day	17% 16% 6% 11% 6% 4 4 3 4 5% 23%	5817
April	1st to 10th	Day	17% 13% 4 7% 4 4 4 3 5% 6% 33%	2400
	11th to 20th	Day	14% 11% 2 7% 4 4 4 4 4 7% 39%	2374
	21st to end	Day	17% 10% 2 7% 4 4 5% 3 5% 7% 35%	2525
May	1st to 10th	Day	18% 7% 3 6% 4 3 4 4 6% 8% 37%	4082
	11th to 20th	Day	14% 8% 2 6% 4 3 4 3 5% 7% 43%	4108
	21st to end	Day	11% 6% 3 6% 4 3 4 3 5% 9% 47%	4824
June	1st to 10th	Day	10% 6% 2 6% 4 4 5% 3 6% 7% 46%	2660
	11th to 20th	Day	9% 5% 2 5% 5% 4 4 4 6% 8% 48%	2660
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 7% 8% 45%	2660
July	1st to 10th	Day	12% 7% 3 7% 4 5% 5% 4 6% 8% 39%	4440
	11th to 20th	Day	7% 3 1 5% 3 3 4 4 7% 9% 52%	4440
	21st to end	Day	7% 5% 2 7% 4 4 6% 4 6% 8% 46%	4813
August	1st to 10th	Day	11% 5% 2 5% 4 3 4 3 5% 7% 50%	4176
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 5% 8% 49%	3927
	21st to end	Day	7% 4 2 6% 5% 5% 5% 3 6% 9% 50%	4180
September	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 6% 8% 47%	2280
	11th to 20th	Day	12% 5% 1 5% 3 4 4 4 6% 8% 48%	2094
	21st to end	Day	14% 7% 3 6% 4 3 5% 4 6% 7% 41%	2090
October	1st to 10th	Day	15% 7% 2 6% 5% 4 4 3 4 6% 44%	2090
	11th to 20th	Day	23% 8% 3 5% 4 4 4 3 5% 7% 33%	1866
	21st to end	Day	24% 11% 3 8% 4 4 5% 3 5% 6% 25%	1881
November	1st to 10th	Day	15% 13% 3 7% 4 3 3 4 5% 6% 37%	1762
	11th to 20th	Day	17% 21% 4 10% 5% 3 4 3 4 5% 24%	1800
	21st to end	Day	21% 17% 6% 10% 5% 4 4 3 3 4 23%	1800
December	1st to 10th	Day	11% 20% 12% 17% 4 3 3 2 4 5% 21%	2678
	11th to 20th	Day	15% 21% 11% 14% 6% 4 4 3 4 4 14%	3008
	21st to end	Day	23% 21% 8% 15% 6% 4 4 2 3 4 10%	3982
January	1st to 10th	Night	15% 22% 10% 21% 4 3 3 3 3 4 10%	6348
	11th to 20th	Night	14% 21% 9% 19% 8% 7% 7% 2 3 2 8%	6360
	21st to end	Night	19% 17% 8% 13% 5% 4 5% 2 3 4 19%	6996
February	1st to 10th	Night	16% 16% 5% 11% 9% 5% 3 3 4 5% 23%	2495
	11th to 20th	Night	15% 15% 4 14% 7% 5% 5% 3 5% 5% 24%	2338
	21st to end	Night	19% 15% 6% 11% 5% 3 3 2 4 4 26%	1980
March	1st to 10th	Night	15% 12% 6% 10% 4 4 3 3 4 5% 33%	5373
	11th to 20th	Night	11% 9% 4 7% 4 4 5% 4 4 6% 42%	5214
	21st to end	Night	19% 13% 6% 9% 4 4 4 3 4 5% 30%	5156
April	1st to 10th	Night	15% 11% 3 7% 5% 5% 4 4 5% 7% 35%	2000
	11th to 20th	Night	19% 9% 2 6% 4 3 4 4 6% 6% 36%	1975
	21st to end	Night	18% 8% 3 7% 4 5% 4 3 5% 6% 35%	1770
May	1st to 10th	Night	17% 8% 3 7% 5% 4 5% 4 5% 8% 35%	2813
	11th to 20th	Night	19% 7% 2 6% 4 3 4 3 5% 7% 41%	2783
	21st to end	Night	15% 6% 2 6% 4 4 3 4 5% 7% 43%	2743
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 6% 9% 48%	1520
	11th to 20th	Night	9% 6% 3 5% 5% 5% 4 4 6% 8% 45%	1520
	21st to end	Night	9% 5% 3 7% 5% 5% 4 5% 8% 8% 42%	1520
July	1st to 10th	Night	10% 4 2 6% 5% 5% 6% 5% 7% 8% 41%	2530
	11th to 20th	Night	9% 4 2 4 4 3 4 3 6% 8% 55%	2530
	21st to end	Night	7% 6% 2 6% 4 4 5% 5% 8% 8% 46%	2750
August	1st to 10th	Night	9% 5% 2 6% 4 5% 4 4 7% 9% 45%	2754
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 5% 8% 50%	2899
	21st to end	Night	10% 5% 2 6% 4 3 4 3 5% 7% 49%	3476
September	1st to 10th	Night	12% 5% 3 6% 4 4 3 4 4 7% 49%	1900
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 5% 9% 53%	2066
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 7% 43%	2090
October	1st to 10th	Night	16% 6% 2 5% 4 4 4 2 5% 7% 46%	2090
	11th to 20th	Night	22% 9% 3 7% 4 3 3 3 4 5% 36%	2311
	21st to end	Night	25% 10% 3 8% 4 3 3 3 4 5% 32%	2717
November	1st to 10th	Night	17% 14% 3 6% 4 3 4 2 5% 5% 37%	2536
	11th to 20th	Night	15% 20% 5% 10% 4 4 4 3 5% 5% 25%	2600
	21st to end	Night	19% 21% 6% 8% 4 3 3 3 4 5% 24%	2600
December	1st to 10th	Night	12% 19% 8% 17% 6% 5% 4 3 4 5% 16%	4508
	11th to 20th	Night	16% 23% 11% 15% 6% 4 3 2 4 4 11%	5199
	21st to end	Night	23% 22% 7% 12% 5% 4 4 3 4 4 10%	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	76% 1 10% 11% 2	3618
	11th to 20th	Day	84% 2 7% 5% 3	3620
	21st to end	Day	70% 2 10% 15% 3	3982
February	1st to 10th	Day	68% 3 10% 12% 6% 1	1900
	11th to 20th	Day	65% 3 9% 16% 7%	1958
	21st to end	Day	62% 3 10% 14% 8% 1	1650
March	1st to 10th	Day	56% 2 10% 22% 10%	4480
	11th to 20th	Day	46% 2 12% 31% 8% 1	4745
	21st to end	Day	66% 2 9% 16% 6% 1	5819
April	1st to 10th	Day	53% 3 9% 22% 12%	2400
	11th to 20th	Day	47% 3 9% 24% 14% 3	2374
	21st to end	Day	49% 3 11% 21% 13% 3	2525
May	1st to 10th	Day	47% 2 10% 28% 11% 1	4120
	11th to 20th	Day	43% 2 13% 30% 12% 1	4112
	21st to end	Day	37% 3 10% 25% 24% 2	4837
June	1st to 10th	Day	37% 4 10% 27% 19% 2	2660
	11th to 20th	Day	35% 4 11% 26% 20% 3	2660
	21st to end	Day	37% 5% 15% 24% 16% 3	2660
July	1st to 10th	Day	43% 5% 12% 21% 17% 3	4371
	11th to 20th	Day	27% 5% 15% 34% 17% 2	4365
	21st to end	Day	35% 6% 15% 20% 21% 3	4662
August	1st to 10th	Day	34% 4 14% 31% 15% 1	4161
	11th to 20th	Day	33% 6% 12% 33% 16% 1	3966
	21st to end	Day	33% 5% 12% 27% 21% 3	4179
September	1st to 10th	Day	36% 5% 14% 25% 17% 4	2280
	11th to 20th	Day	34% 4 11% 30% 19% 2	2094
	21st to end	Day	41% 5% 9% 27% 17% 1	2090
October	1st to 10th	Day	30% 3 8% 36% 22% 1	3480
	11th to 20th	Day	40% 4 11% 22% 23%	3069
	21st to end	Day	52% 2 9% 25% 10% 2	3081
November	1st to 10th	Day	49% 3 13% 21% 13% 1	1762
	11th to 20th	Day	64% 2 9% 17% 7% 1	1800
	21st to end	Day	68% 2 9% 17% 5%	1800
December	1st to 10th	Day	69% 2 15% 11% 3	2678
	11th to 20th	Day	75% 3 11% 10% 1	3005
	21st to end	Day	81% 2 6% 9% 2	3982
January	1st to 10th	Night	79% 1 6% 11% 2	6348
	11th to 20th	Night	85% 2 7% 5% 2	6360
	21st to end	Night	72% 2 13% 10% 3	6996
February	1st to 10th	Night	66% 3 9% 14% 7% 1	2495
	11th to 20th	Night	64% 2 10% 17% 7% 1	2339
	21st to end	Night	63% 2 9% 17% 7% 2	1980
March	1st to 10th	Night	55% 2 11% 24% 7% 1	5373
	11th to 20th	Night	45% 2 11% 29% 11% 2	5214
	21st to end	Night	58% 2 10% 20% 10% 1	5156
April	1st to 10th	Night	50% 4 11% 21% 13% 1	2000
	11th to 20th	Night	49% 3 8% 22% 16% 3	1975
	21st to end	Night	49% 4 10% 20% 15% 2	1770
May	1st to 10th	Night	49% 2 11% 24% 12% 1	2840
	11th to 20th	Night	45% 2 12% 25% 15% 1	2784
	21st to end	Night	42% 3 10% 20% 24% 2	2751
June	1st to 10th	Night	33% 4 11% 30% 19% 3	1520
	11th to 20th	Night	37% 4 12% 24% 20% 2	1520
	21st to end	Night	38% 4 18% 24% 14% 2	1520
July	1st to 10th	Night	38% 5% 14% 24% 13% 6%	2490
	11th to 20th	Night	28% 5% 13% 24% 28% 3	2482
	21st to end	Night	34% 5% 17% 18% 23% 3	2662
August	1st to 10th	Night	35% 5% 13% 30% 16% 1	2745
	11th to 20th	Night	33% 5% 11% 29% 21% 1	2926
	21st to end	Night	35% 4 8% 30% 20% 3	3476
September	1st to 10th	Night	37% 4 11% 24% 19% 5%	1900
	11th to 20th	Night	31% 3 8% 31% 25% 2	2066
	21st to end	Night	41% 3 10% 27% 18% 2	2090
October	1st to 10th	Night	28% 3 9% 33% 26% 2	3480
	11th to 20th	Night	45% 2 7% 21% 23% 1	3847
	21st to end	Night	45% 2 8% 27% 16% 1	4467
November	1st to 10th	Night	51% 3 8% 22% 14% 2	2536
	11th to 20th	Night	62% 3 10% 16% 8% 1	2600
	21st to end	Night	65% 2 11% 17% 5%	2600
December	1st to 10th	Night	71% 3 12% 11% 3	4508
	11th to 20th	Night	79% 2 9% 8% 2	5201
	21st to end	Night	79% 2 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	21% 21% 37% 15% 5% 1	300
	11th to 20th	Day	24% 23% 36% 11% 4 1	300
	21st to end	Day	25% 24% 32% 16% 3	330
February	1st to 10th	Day	30% 23% 31% 12% 3 1	300
	11th to 20th	Day	26% 29% 32% 11% 1	300
	21st to end	Day	29% 30% 31% 7% 2	249
March	1st to 10th	Day	24% 27% 36% 11% 2	300
	11th to 20th	Day	26% 21% 31% 17% 5% 1	395
	21st to end	Day	31% 19% 29% 15% 6% 1	550
April	1st to 10th	Day	27% 21% 28% 19% 3 1	500
	11th to 20th	Day	24% 24% 28% 15% 7% 2	492
	21st to end	Day	25% 18% 31% 17% 7% 3	480
May	1st to 10th	Day	25% 16% 30% 19% 8% 2	463
	11th to 20th	Day	21% 15% 28% 24% 9% 4	501
	21st to end	Day	14% 12% 31% 25% 14% 4	734
June	1st to 10th	Day	11% 13% 31% 29% 12% 4	680
	11th to 20th	Day	13% 9% 30% 32% 13% 3	680
	21st to end	Day	14% 10% 33% 26% 12% 4	680
July	1st to 10th	Day	9% 7% 26% 27% 22% 9%	671
	11th to 20th	Day	11% 6% 31% 27% 18% 7%	668
	21st to end	Day	8% 5% 26% 36% 19% 6%	739
August	1st to 10th	Day	8% 4 22% 29% 24% 12%	533
	11th to 20th	Day	11% 6% 25% 25% 24% 9%	479
	21st to end	Day	9% 4 22% 34% 23% 9%	539
September	1st to 10th	Day	15% 5% 23% 30% 20% 6%	490
	11th to 20th	Day	10% 7% 19% 29% 26% 10%	490
	21st to end	Day	19% 12% 21% 25% 14% 8%	490
October	1st to 10th	Day	17% 10% 28% 26% 17% 3	490
	11th to 20th	Day	25% 18% 30% 20% 7%	352
	21st to end	Day	36% 14% 34% 15% 2 1	330
November	1st to 10th	Day	18% 18% 38% 18% 6% 2	300
	11th to 20th	Day	28% 27% 26% 14% 5%	300
	21st to end	Day	34% 19% 34% 12% 1	300
December	1st to 10th	Day	24% 31% 29% 12% 4 1	300
	11th to 20th	Day	22% 31% 32% 12% 2 1	300
	21st to end	Day	24% 30% 33% 12% 2	330
January	1st to 10th	Night	25% 17% 35% 18% 4	1000
	11th to 20th	Night	26% 17% 35% 18% 4 1	1000
	21st to end	Night	24% 17% 34% 22% 3	1100
February	1st to 10th	Night	27% 16% 33% 22% 3	855
	11th to 20th	Night	23% 19% 33% 21% 4	783
	21st to end	Night	28% 18% 34% 17% 4	660
March	1st to 10th	Night	23% 17% 31% 22% 7% 1	800
	11th to 20th	Night	20% 13% 34% 26% 6%	800
	21st to end	Night	25% 13% 26% 29% 6%	750
April	1st to 10th	Night	20% 16% 33% 25% 6% 1	600
	11th to 20th	Night	24% 13% 30% 25% 7% 1	593
	21st to end	Night	21% 12% 30% 27% 9% 1	587
May	1st to 10th	Night	22% 7% 30% 30% 11% 1	570
	11th to 20th	Night	20% 7% 23% 36% 14% 1	561
	21st to end	Night	14% 4 23% 38% 20% 1	617
June	1st to 10th	Night	11% 5% 24% 41% 18% 2	570
	11th to 20th	Night	13% 3 29% 37% 16% 1	570
	21st to end	Night	11% 6% 23% 37% 22% 2	570
July	1st to 10th	Night	8% 3 16% 39% 30% 4	555
	11th to 20th	Night	10% 5% 19% 36% 27% 4	552
	21st to end	Night	8% 3 14% 44% 29% 2	624
August	1st to 10th	Night	9% 2 13% 43% 29% 3	567
	11th to 20th	Night	9% 3 14% 38% 30% 5%	564
	21st to end	Night	11% 3 13% 41% 29% 3	627
September	1st to 10th	Night	14% 4 17% 37% 24% 5%	570
	11th to 20th	Night	13% 4 15% 37% 27% 4	736
	21st to end	Night	16% 8% 23% 29% 21% 3	760
October	1st to 10th	Night	19% 7% 25% 29% 19% 1	760
	11th to 20th	Night	27% 15% 23% 27% 7% 1	760
	21st to end	Night	30% 15% 26% 23% 6%	836
November	1st to 10th	Night	26% 12% 30% 22% 10% 1	780
	11th to 20th	Night	27% 18% 30% 20% 4 1	800
	21st to end	Night	32% 14% 30% 21% 4	800
December	1st to 10th	Night	29% 20% 31% 17% 4	954
	11th to 20th	Night	27% 15% 36% 18% 4	1000
	21st to end	Night	32% 16% 33% 17% 2	1100

Page generated at 2025-04-23 09:25:07. Version ac07

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