Elk River WMA
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elk River WMA clear sky chart from 2005-11-06 to 2025-03-12.

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	17% 11% 3 8% 5% 4 4 4 5% 7% 32%	108639
	Night	18% 12% 4 8% 5% 4 4 3 5% 6% 32%	110376
Transparency	Day	50% 6% 10% 20% 12% 2	112301
	Night	53% 5% 9% 19% 12% 2	114853
Seeing	Day	27% 13% 24% 21% 12% 4	15310
	Night	26% 11% 22% 27% 12% 2	25750

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	16% 21% 9% 16% 8% 3 3 2 3 4 15%	4056
	11th to 20th	Day	18% 24% 8% 11% 6% 4 3 1 2 3 19%	4060
	21st to end	Day	18% 17% 5% 11% 5% 3 3 3 4 5% 26%	4466
February	1st to 10th	Day	21% 16% 4 10% 6% 4 4 3 4 5% 25%	1800
	11th to 20th	Day	22% 17% 4 10% 4 5% 4 2 4 4 24%	1804
	21st to end	Day	23% 16% 4 9% 4 3 3 3 4 4 28%	1675
March	1st to 10th	Day	20% 17% 4 7% 4 3 3 3 5% 6% 28%	3545
	11th to 20th	Day	17% 9% 4 7% 4 4 4 3 5% 6% 37%	3491
	21st to end	Day	23% 11% 3 7% 5% 4 4 3 5% 6% 29%	3815
April	1st to 10th	Day	18% 14% 3 6% 4 4 4 3 5% 7% 32%	2146
	11th to 20th	Day	17% 9% 3 6% 4 4 3 3 5% 7% 39%	2279
	21st to end	Day	22% 8% 2 6% 5% 4 5% 4 5% 6% 32%	2470
May	1st to 10th	Day	23% 9% 3 9% 6% 5% 5% 4 6% 7% 26%	4082
	11th to 20th	Day	21% 9% 3 7% 5% 4 4 4 5% 7% 31%	4081
	21st to end	Day	12% 6% 2 7% 6% 5% 6% 5% 8% 10% 34%	4476
June	1st to 10th	Day	14% 6% 3 6% 5% 5% 6% 5% 6% 8% 36%	2470
	11th to 20th	Day	12% 6% 2 8% 6% 6% 5% 5% 7% 9% 33%	2470
	21st to end	Day	13% 6% 3 7% 5% 5% 5% 5% 7% 10% 36%	2470
July	1st to 10th	Day	10% 5% 2 7% 5% 5% 5% 5% 6% 9% 41%	4120
	11th to 20th	Day	13% 6% 2 6% 5% 5% 5% 4 7% 9% 39%	4120
	21st to end	Day	19% 9% 3 8% 5% 5% 5% 4 6% 7% 29%	4466
August	1st to 10th	Day	13% 7% 3 7% 6% 6% 5% 5% 7% 9% 32%	4104
	11th to 20th	Day	14% 5% 2 7% 5% 6% 6% 5% 7% 8% 34%	4044
	21st to end	Day	8% 4 1 5% 4 4 5% 4 7% 10% 48%	4313
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 5% 7% 44%	2216
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 5% 8% 43%	2090
	21st to end	Day	19% 9% 2 7% 4 3 3 4 5% 7% 37%	2090
October	1st to 10th	Day	18% 5% 2 5% 4 3 3 3 5% 7% 45%	1933
	11th to 20th	Day	19% 9% 2 5% 4 4 3 3 5% 5% 41%	1900
	21st to end	Day	22% 9% 2 5% 3 3 4 3 4 6% 39%	2090
November	1st to 10th	Day	14% 8% 3 6% 4 3 3 3 4 5% 46%	1903
	11th to 20th	Day	17% 13% 3 6% 4 4 5% 4 6% 7% 34%	1800
	21st to end	Day	18% 16% 4 6% 3 5% 4 3 4 6% 31%	1675
December	1st to 10th	Day	22% 13% 4 18% 4 3 4 3 3 3 23%	2600
	11th to 20th	Day	24% 16% 4 8% 4 3 3 4 5% 6% 24%	3053
	21st to end	Day	19% 16% 5% 9% 6% 5% 5% 4 5% 7% 19%	4466
January	1st to 10th	Night	18% 23% 7% 17% 4 3 2 2 3 4 18%	5889
	11th to 20th	Night	19% 18% 7% 17% 7% 4 2 2 3 4 18%	5900
	21st to end	Night	22% 13% 5% 9% 6% 4 3 2 3 4 28%	6490
February	1st to 10th	Night	20% 15% 5% 9% 6% 3 3 3 4 5% 26%	2600
	11th to 20th	Night	22% 17% 4 10% 6% 4 4 3 4 4 23%	2478
	21st to end	Night	24% 14% 5% 8% 4 3 3 3 4 7% 25%	1953
March	1st to 10th	Night	24% 13% 3 6% 4 4 3 3 4 6% 30%	3528
	11th to 20th	Night	18% 16% 6% 6% 3 3 3 2 3 6% 34%	3498
	21st to end	Night	20% 10% 3 6% 3 4 4 4 5% 6% 36%	3817
April	1st to 10th	Night	19% 13% 3 6% 4 4 4 4 4 6% 34%	2033
	11th to 20th	Night	16% 8% 2 6% 4 4 4 4 7% 8% 38%	1866
	21st to end	Night	17% 8% 2 8% 5% 4 5% 4 5% 6% 36%	1710
May	1st to 10th	Night	27% 11% 4 8% 5% 5% 4 3 4 6% 25%	2813
	11th to 20th	Night	19% 10% 4 8% 5% 4 3 3 5% 7% 32%	2812
	21st to end	Night	16% 8% 3 7% 5% 5% 5% 4 6% 8% 32%	3079
June	1st to 10th	Night	12% 6% 3 6% 4 5% 5% 5% 6% 8% 40%	1710
	11th to 20th	Night	10% 6% 3 7% 5% 5% 5% 5% 7% 9% 38%	1710
	21st to end	Night	13% 6% 2 5% 4 4 4 4 8% 10% 41%	1710
July	1st to 10th	Night	12% 6% 2 6% 4 5% 5% 5% 7% 11% 36%	2840
	11th to 20th	Night	14% 6% 2 6% 4 4 5% 4 8% 9% 39%	2840
	21st to end	Night	14% 8% 3 8% 5% 5% 5% 4 7% 8% 32%	3087
August	1st to 10th	Night	15% 7% 3 7% 5% 5% 5% 4 7% 9% 31%	2825
	11th to 20th	Night	19% 6% 3 7% 4 5% 4 3 6% 7% 36%	2785
	21st to end	Night	7% 5% 1 6% 4 5% 5% 4 5% 9% 49%	3311
September	1st to 10th	Night	13% 6% 2 6% 4 4 5% 4 6% 7% 43%	1960
	11th to 20th	Night	14% 5% 2 4 3 4 4 2 5% 6% 51%	2090
	21st to end	Night	16% 7% 2 5% 4 5% 5% 3 5% 7% 41%	2090
October	1st to 10th	Night	16% 4 2 6% 4 3 4 4 5% 7% 46%	2247
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 5% 6% 42%	2280
	21st to end	Night	23% 7% 2 5% 4 3 4 3 4 5% 41%	2508
November	1st to 10th	Night	15% 9% 3 5% 4 3 4 3 4 5% 45%	2391
	11th to 20th	Night	20% 14% 3 5% 3 3 3 4 5% 6% 33%	2600
	21st to end	Night	19% 14% 4 8% 5% 4 5% 3 4 5% 31%	2720
December	1st to 10th	Night	18% 15% 5% 16% 4 3 3 3 4 5% 24%	4580
	11th to 20th	Night	23% 17% 7% 9% 4 4 3 2 3 4 25%	5136
	21st to end	Night	19% 18% 4 9% 6% 5% 4 3 5% 6% 21%	6490

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	75% 3 7% 10% 5%	4057
	11th to 20th	Day	74% 2 4 11% 8%	4060
	21st to end	Day	62% 2 7% 18% 8% 1	4466
February	1st to 10th	Day	64% 4 8% 16% 8%	1800
	11th to 20th	Day	65% 4 7% 14% 9% 1	1813
	21st to end	Day	61% 4 7% 16% 11% 1	1675
March	1st to 10th	Day	57% 4 9% 20% 10% 1	3545
	11th to 20th	Day	47% 5% 9% 25% 13% 1	3491
	21st to end	Day	56% 5% 7% 19% 12% 1	3815
April	1st to 10th	Day	53% 5% 10% 16% 14% 3	2146
	11th to 20th	Day	46% 5% 10% 19% 17% 3	2279
	21st to end	Day	52% 6% 10% 19% 12% 2	2470
May	1st to 10th	Day	58% 6% 8% 19% 7% 1	4120
	11th to 20th	Day	51% 8% 10% 19% 11% 1	4085
	21st to end	Day	42% 8% 17% 19% 11% 4	4489
June	1st to 10th	Day	43% 8% 12% 21% 15% 1	2470
	11th to 20th	Day	45% 9% 13% 21% 12% 1	2470
	21st to end	Day	43% 8% 14% 23% 11% 1	2470
July	1st to 10th	Day	39% 8% 15% 23% 12% 3	4055
	11th to 20th	Day	40% 8% 12% 29% 11% 1	4051
	21st to end	Day	52% 7% 10% 16% 14% 1	4324
August	1st to 10th	Day	46% 8% 15% 24% 7%	4091
	11th to 20th	Day	44% 8% 10% 27% 11% 1	4083
	21st to end	Day	31% 7% 15% 32% 15% 1	4313
September	1st to 10th	Day	39% 6% 10% 19% 20% 4	2216
	11th to 20th	Day	39% 7% 11% 24% 18% 2	2090
	21st to end	Day	47% 5% 9% 22% 15% 1	2090
October	1st to 10th	Day	31% 4 7% 26% 29% 3	3206
	11th to 20th	Day	41% 4 9% 20% 19% 8%	3140
	21st to end	Day	32% 3 9% 30% 20% 5%	3428
November	1st to 10th	Day	42% 4 7% 25% 18% 4	1903
	11th to 20th	Day	50% 5% 8% 18% 16% 4	1800
	21st to end	Day	56% 4 9% 18% 12% 1	1675
December	1st to 10th	Day	68% 3 7% 18% 4 1	2600
	11th to 20th	Day	62% 4 9% 15% 9%	3049
	21st to end	Day	63% 5% 10% 16% 6%	4466
January	1st to 10th	Night	74% 2 6% 12% 4 1	5889
	11th to 20th	Night	73% 3 5% 11% 6% 1	5900
	21st to end	Night	63% 3 7% 17% 9% 1	6490
February	1st to 10th	Night	62% 4 9% 15% 9%	2600
	11th to 20th	Night	67% 3 7% 14% 9% 1	2480
	21st to end	Night	62% 4 7% 15% 9% 3	1953
March	1st to 10th	Night	56% 4 7% 22% 11% 1	3528
	11th to 20th	Night	54% 4 8% 22% 12%	3498
	21st to end	Night	49% 5% 8% 20% 16% 2	3817
April	1st to 10th	Night	53% 5% 8% 18% 13% 2	2033
	11th to 20th	Night	43% 6% 13% 18% 15% 5%	1866
	21st to end	Night	49% 5% 13% 19% 13% 2	1710
May	1st to 10th	Night	61% 6% 7% 15% 9% 1	2840
	11th to 20th	Night	51% 8% 11% 19% 9% 1	2813
	21st to end	Night	47% 9% 14% 19% 8% 3	3087
June	1st to 10th	Night	40% 8% 14% 23% 14% 1	1710
	11th to 20th	Night	41% 11% 13% 21% 13% 2	1710
	21st to end	Night	37% 9% 15% 24% 14% 1	1710
July	1st to 10th	Night	41% 9% 15% 20% 14% 1	2795
	11th to 20th	Night	39% 8% 13% 28% 10% 2	2786
	21st to end	Night	48% 9% 11% 17% 13% 1	2988
August	1st to 10th	Night	48% 8% 15% 21% 7% 1	2814
	11th to 20th	Night	46% 6% 10% 22% 14% 1	2812
	21st to end	Night	32% 6% 12% 33% 16% 1	3311
September	1st to 10th	Night	39% 6% 14% 19% 17% 4	1960
	11th to 20th	Night	35% 5% 11% 23% 22% 3	2090
	21st to end	Night	43% 6% 10% 22% 17% 1	2090
October	1st to 10th	Night	33% 5% 9% 27% 24% 4	3754
	11th to 20th	Night	39% 4 7% 20% 22% 8%	3779
	21st to end	Night	34% 3 6% 28% 24% 5%	4120
November	1st to 10th	Night	42% 4 9% 18% 20% 6%	2391
	11th to 20th	Night	53% 4 7% 15% 17% 4	2600
	21st to end	Night	57% 5% 7% 17% 13% 2	2720
December	1st to 10th	Night	65% 3 8% 18% 5% 1	4580
	11th to 20th	Night	66% 3 8% 15% 8%	5139
	21st to end	Night	65% 4 9% 15% 7%	6490

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	37% 29% 20% 10% 3	300
	11th to 20th	Day	44% 25% 24% 8%	300
	21st to end	Day	41% 24% 25% 8% 2	330
February	1st to 10th	Day	40% 23% 27% 8% 2	300
	11th to 20th	Day	52% 21% 19% 7% 1	300
	21st to end	Day	42% 20% 29% 8%	274
March	1st to 10th	Day	37% 19% 27% 13% 4	500
	11th to 20th	Day	36% 23% 22% 13% 5% 1	464
	21st to end	Day	37% 17% 27% 15% 4 1	506
April	1st to 10th	Day	35% 20% 23% 18% 4	460
	11th to 20th	Day	29% 14% 29% 15% 9% 3	452
	21st to end	Day	34% 17% 25% 15% 7% 2	460
May	1st to 10th	Day	34% 14% 28% 12% 9% 3	463
	11th to 20th	Day	29% 11% 27% 20% 10% 3	487
	21st to end	Day	18% 8% 25% 24% 19% 6%	529
June	1st to 10th	Day	17% 10% 24% 27% 15% 7%	490
	11th to 20th	Day	19% 8% 27% 23% 17% 7%	490
	21st to end	Day	14% 11% 29% 26% 14% 5%	490
July	1st to 10th	Day	15% 7% 18% 27% 21% 11%	485
	11th to 20th	Day	12% 6% 22% 33% 18% 9%	484
	21st to end	Day	20% 7% 22% 24% 18% 9%	532
August	1st to 10th	Day	14% 6% 21% 32% 18% 9%	486
	11th to 20th	Day	17% 5% 20% 31% 18% 9%	479
	21st to end	Day	14% 4 19% 31% 22% 10%	539
September	1st to 10th	Day	16% 7% 16% 29% 24% 9%	490
	11th to 20th	Day	15% 4 14% 33% 24% 10%	490
	21st to end	Day	25% 7% 26% 23% 15% 3	490
October	1st to 10th	Day	20% 9% 25% 24% 17% 6%	490
	11th to 20th	Day	25% 12% 24% 23% 13% 2	490
	21st to end	Day	27% 15% 26% 23% 9% 1	539
November	1st to 10th	Day	23% 12% 28% 26% 10% 2	441
	11th to 20th	Day	36% 14% 27% 16% 7% 1	300
	21st to end	Day	33% 18% 32% 14% 2 1	237
December	1st to 10th	Day	39% 20% 26% 12% 3 1	200
	11th to 20th	Day	39% 15% 26% 15% 6%	213
	21st to end	Day	38% 19% 26% 13% 4	330
January	1st to 10th	Night	37% 19% 26% 13% 4	800
	11th to 20th	Night	38% 18% 24% 18% 2	800
	21st to end	Night	34% 18% 28% 18% 1	880
February	1st to 10th	Night	32% 18% 26% 21% 3	800
	11th to 20th	Night	37% 21% 27% 13% 1	783
	21st to end	Night	38% 17% 29% 15% 1	660
March	1st to 10th	Night	33% 16% 26% 22% 3	800
	11th to 20th	Night	34% 18% 24% 17% 6% 1	767
	21st to end	Night	33% 14% 28% 20% 5%	836
April	1st to 10th	Night	30% 16% 29% 21% 4	760
	11th to 20th	Night	21% 13% 30% 25% 10% 1	742
	21st to end	Night	24% 10% 32% 26% 8%	570
May	1st to 10th	Night	26% 11% 26% 26% 10% 1	570
	11th to 20th	Night	25% 7% 25% 31% 11% 1	561
	21st to end	Night	15% 4 22% 34% 21% 5%	617
June	1st to 10th	Night	14% 5% 19% 38% 22% 2	570
	11th to 20th	Night	14% 4 17% 40% 23% 2	570
	21st to end	Night	17% 3 19% 41% 19% 2	570
July	1st to 10th	Night	15% 5% 11% 39% 25% 5%	555
	11th to 20th	Night	13% 4 13% 38% 27% 5%	552
	21st to end	Night	15% 3 9% 38% 29% 5%	624
August	1st to 10th	Night	14% 4 11% 39% 30% 3	567
	11th to 20th	Night	17% 4 10% 36% 28% 5%	564
	21st to end	Night	13% 3 10% 39% 30% 6%	736
September	1st to 10th	Night	17% 4 15% 33% 28% 4	760
	11th to 20th	Night	15% 4 14% 34% 28% 4	760
	21st to end	Night	19% 6% 22% 29% 22% 2	760
October	1st to 10th	Night	18% 6% 19% 33% 21% 3	760
	11th to 20th	Night	25% 9% 23% 28% 13% 2	760
	21st to end	Night	30% 9% 22% 28% 10% 1	836
November	1st to 10th	Night	21% 10% 23% 31% 14% 1	780
	11th to 20th	Night	32% 13% 25% 22% 8% 1	800
	21st to end	Night	30% 14% 26% 24% 5% 1	800
December	1st to 10th	Night	38% 16% 22% 20% 4	800
	11th to 20th	Night	31% 20% 23% 23% 3	800
	21st to end	Night	33% 15% 28% 22% 2	880

Page generated at 2025-03-09 08:08:48. Version ac07

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