Wheatland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wheatland clear sky chart from 2005-11-06 to 2026-08-30.

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	6% 5% 2 5% 4 4 4 4 6% 8% 53%	153131
	Night	6% 6% 2 5% 4 4 4 3 5% 7% 53%	146628
Transparency	Day	29% 3 10% 26% 22% 10%	147995
	Night	31% 3 11% 28% 20% 7%	142776
Seeing	Day	11% 11% 28% 29% 17% 5%	18306
	Night	10% 11% 33% 35% 10% 1	28222

By Month

Percentage Cloud Cover SW (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	3 10% 4 9% 4 4 4 3 5% 7% 48%	4720
	11th to 20th	Day	3 9% 3 6% 5% 5% 4 4 5% 8% 47%	4740
	21st to end	Day	1 6% 2 7% 4 4 3 3 5% 7% 57%	5664
February	1st to 10th	Day	4 9% 4 7% 5% 3 3 4 6% 9% 46%	1890
	11th to 20th	Day	3 9% 4 8% 6% 5% 4 4 5% 8% 45%	1971
	21st to end	Day	4 7% 3 6% 4 3 4 2 5% 7% 55%	1730
March	1st to 10th	Day	6% 9% 3 6% 3 4 4 3 4 8% 51%	4600
	11th to 20th	Day	6% 7% 3 7% 4 4 4 4 5% 7% 51%	4987
	21st to end	Day	7% 8% 3 6% 5% 5% 5% 4 6% 8% 44%	5966
April	1st to 10th	Day	9% 9% 3 5% 4 4 4 3 6% 7% 48%	2520
	11th to 20th	Day	12% 9% 3 6% 4 5% 5% 4 6% 7% 39%	2491
	21st to end	Day	11% 7% 2 6% 5% 4 5% 4 5% 8% 43%	2527
May	1st to 10th	Day	14% 6% 2 4 3 3 4 4 5% 7% 48%	7899
	11th to 20th	Day	11% 5% 1 5% 4 4 5% 4 7% 8% 46%	8191
	21st to end	Day	11% 4 2 4 4 4 4 4 6% 8% 49%	9026
June	1st to 10th	Day	5% 3 2 4 4 4 5% 5% 8% 11% 49%	2940
	11th to 20th	Day	7% 3 1 4 3 4 5% 4 6% 9% 54%	2940
	21st to end	Day	5% 2 1 4 3 4 5% 4 7% 8% 56%	2940
July	1st to 10th	Day	3 2 1 4 3 4 4 4 7% 8% 59%	8249
	11th to 20th	Day	3 1 1 2 3 3 4 4 7% 8% 63%	8250
	21st to end	Day	6% 3 1 5% 3 4 5% 4 8% 9% 50%	8957
August	1st to 10th	Day	6% 3 1 4 4 4 5% 5% 7% 8% 53%	6077
	11th to 20th	Day	3 2 1 4 4 4 5% 4 6% 8% 60%	5617
	21st to end	Day	6% 4 2 5% 4 4 4 4 7% 7% 52%	6093
September	1st to 10th	Day	6% 3 1 3 3 3 4 3 5% 6% 64%	2400
	11th to 20th	Day	7% 3 1 3 3 3 3 3 5% 7% 62%	2376
	21st to end	Day	6% 3 2 3 3 3 3 3 4 7% 65%	2200
October	1st to 10th	Day	5% 3 1 3 2 2 2 2 3 4 74%	3279
	11th to 20th	Day	10% 4 2 4 3 3 3 3 4 5% 59%	3250
	21st to end	Day	8% 7% 2 4 2 3 3 3 4 6% 58%	3325
November	1st to 10th	Day	4 5% 2 4 4 4 3 4 6% 8% 56%	1853
	11th to 20th	Day	4 5% 2 3 3 3 3 3 6% 8% 60%	1885
	21st to end	Day	3 8% 3 6% 3 3 3 4 7% 7% 53%	1680
December	1st to 10th	Day	2 6% 3 4 3 3 3 3 4 6% 63%	2700
	11th to 20th	Day	3 6% 3 6% 3 3 3 3 5% 8% 57%	3106
	21st to end	Day	6% 9% 3 7% 5% 4 4 3 5% 7% 48%	4092
January	1st to 10th	Night	4 10% 4 8% 4 4 4 4 5% 7% 48%	8201
	11th to 20th	Night	3 8% 4 7% 5% 4 4 3 5% 6% 51%	8250
	21st to end	Night	2 7% 4 9% 5% 4 4 3 4 5% 54%	8593
February	1st to 10th	Night	4 8% 3 8% 4 5% 5% 3 6% 8% 46%	2730
	11th to 20th	Night	4 11% 4 7% 5% 4 5% 3 6% 6% 46%	2534
	21st to end	Night	2 8% 3 7% 4 3 4 3 5% 7% 54%	2076
March	1st to 10th	Night	7% 10% 2 4 2 3 3 3 4 8% 54%	5494
	11th to 20th	Night	6% 9% 3 6% 3 3 3 3 5% 7% 52%	5211
	21st to end	Night	11% 11% 3 7% 4 4 4 4 5% 6% 41%	5235
April	1st to 10th	Night	10% 7% 3 5% 3 4 4 3 5% 7% 49%	2100
	11th to 20th	Night	11% 7% 2 6% 5% 3 4 4 5% 6% 46%	2077
	21st to end	Night	13% 8% 2 7% 4 3 4 3 5% 7% 44%	2090
May	1st to 10th	Night	14% 8% 2 6% 3 3 3 3 4 6% 50%	5032
	11th to 20th	Night	12% 5% 2 5% 4 3 4 3 6% 7% 49%	4701
	21st to end	Night	12% 4 2 4 3 4 5% 4 6% 9% 48%	5181
June	1st to 10th	Night	6% 4 1 4 4 3 4 4 7% 9% 55%	1680
	11th to 20th	Night	7% 3 1 3 3 3 4 5% 6% 9% 56%	1680
	21st to end	Night	4 2 1 4 3 3 4 4 5% 8% 62%	1680
July	1st to 10th	Night	5% 3 1 5% 4 4 5% 5% 7% 8% 52%	4740
	11th to 20th	Night	4 2 1 3 3 4 4 4 5% 8% 62%	4740
	21st to end	Night	6% 3 1 6% 4 6% 7% 5% 8% 9% 44%	5152
August	1st to 10th	Night	10% 3 1 4 3 4 5% 3 6% 8% 53%	3952
	11th to 20th	Night	3 2 1 5% 4 5% 6% 4 7% 9% 54%	4450
	21st to end	Night	7% 4 2 6% 4 4 5% 3 6% 8% 52%	5083
September	1st to 10th	Night	6% 4 1 3 3 2 3 3 4 6% 64%	2000
	11th to 20th	Night	7% 3 1 4 3 3 3 3 5% 6% 61%	2023
	21st to end	Night	8% 3 1 3 3 2 3 2 4 6% 65%	2200
October	1st to 10th	Night	6% 3 1 2 2 2 2 2 3 4 74%	3909
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 4 6% 58%	3898
	21st to end	Night	8% 6% 2 4 3 2 3 3 5% 6% 59%	4442
November	1st to 10th	Night	6% 5% 2 5% 3 3 3 3 5% 8% 57%	2665
	11th to 20th	Night	4 6% 2 5% 4 4 4 4 6% 7% 54%	2730
	21st to end	Night	4 8% 2 5% 3 3 4 3 5% 7% 56%	2940
December	1st to 10th	Night	3 6% 3 5% 3 3 3 2 4 5% 63%	4710
	11th to 20th	Night	3 8% 3 5% 4 4 4 3 5% 6% 56%	5321
	21st to end	Night	7% 10% 3 7% 4 4 4 4 6% 7% 45%	7128

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	38% 2 13% 28% 18% 1	4723
	11th to 20th	Day	35% 4 16% 24% 19% 4	4740
	21st to end	Day	27% 3 14% 30% 22% 4	5664
February	1st to 10th	Day	36% 3 15% 28% 15% 3	1890
	11th to 20th	Day	38% 3 10% 28% 16% 5%	1980
	21st to end	Day	29% 3 15% 27% 20% 6%	1730
March	1st to 10th	Day	33% 2 5% 28% 26% 5%	4600
	11th to 20th	Day	34% 3 12% 29% 19% 3	4987
	21st to end	Day	38% 3 14% 32% 12% 2	5966
April	1st to 10th	Day	35% 4 14% 25% 17% 5%	2520
	11th to 20th	Day	43% 4 8% 21% 18% 5%	2494
	21st to end	Day	39% 4 10% 27% 18% 2	2527
May	1st to 10th	Day	36% 3 9% 30% 18% 4	7899
	11th to 20th	Day	35% 3 8% 25% 21% 7%	8195
	21st to end	Day	32% 3 12% 30% 19% 4	9027
June	1st to 10th	Day	26% 4 16% 28% 19% 7%	2940
	11th to 20th	Day	27% 4 11% 24% 20% 15%	2940
	21st to end	Day	24% 4 8% 24% 26% 15%	2940
July	1st to 10th	Day	20% 4 6% 22% 28% 20%	8181
	11th to 20th	Day	17% 3 7% 24% 24% 25%	8175
	21st to end	Day	28% 3 13% 17% 20% 18%	8759
August	1st to 10th	Day	27% 3 10% 25% 21% 14%	4455
	11th to 20th	Day	26% 3 8% 21% 24% 18%	4099
	21st to end	Day	22% 3 7% 19% 26% 23%	4420
September	1st to 10th	Day	22% 3 5% 21% 30% 20%	2400
	11th to 20th	Day	23% 2 5% 24% 29% 17%	2376
	21st to end	Day	21% 3 6% 27% 33% 11%	2200
October	1st to 10th	Day	17% 2 6% 18% 28% 29%	3279
	11th to 20th	Day	29% 2 9% 27% 26% 7%	3250
	21st to end	Day	27% 3 8% 30% 27% 5%	3325
November	1st to 10th	Day	26% 2 11% 28% 25% 7%	1853
	11th to 20th	Day	23% 2 12% 34% 25% 5%	1885
	21st to end	Day	29% 3 10% 30% 25% 3	1680
December	1st to 10th	Day	23% 3 12% 35% 24% 2	2700
	11th to 20th	Day	27% 3 14% 37% 16% 3	3104
	21st to end	Day	37% 2 10% 34% 15% 2	4092
January	1st to 10th	Night	37% 2 12% 31% 15% 3	8202
	11th to 20th	Night	34% 5% 14% 26% 17% 4	8250
	21st to end	Night	34% 2 14% 29% 18% 3	8593
February	1st to 10th	Night	36% 4 15% 28% 14% 3	2730
	11th to 20th	Night	38% 4 12% 26% 15% 4	2535
	21st to end	Night	30% 3 11% 28% 24% 4	2076
March	1st to 10th	Night	31% 2 5% 31% 24% 6%	5494
	11th to 20th	Night	32% 3 10% 26% 25% 4	5211
	21st to end	Night	44% 2 17% 24% 12% 1	5235
April	1st to 10th	Night	35% 4 12% 27% 17% 5%	2100
	11th to 20th	Night	38% 3 10% 24% 19% 5%	2077
	21st to end	Night	41% 2 9% 27% 19% 2	2090
May	1st to 10th	Night	37% 2 9% 29% 21% 2	5033
	11th to 20th	Night	35% 3 11% 29% 16% 7%	4702
	21st to end	Night	34% 3 16% 30% 15% 2	5182
June	1st to 10th	Night	25% 4 21% 28% 17% 6%	1680
	11th to 20th	Night	24% 3 13% 25% 22% 12%	1680
	21st to end	Night	21% 4 11% 27% 24% 13%	1680
July	1st to 10th	Night	27% 4 11% 24% 21% 12%	4700
	11th to 20th	Night	20% 3 10% 27% 21% 18%	4692
	21st to end	Night	35% 4 15% 17% 18% 11%	5038
August	1st to 10th	Night	31% 3 12% 25% 20% 9%	2898
	11th to 20th	Night	29% 4 12% 24% 18% 14%	3244
	21st to end	Night	22% 3 11% 20% 25% 19%	3687
September	1st to 10th	Night	23% 2 6% 23% 29% 18%	2000
	11th to 20th	Night	24% 2 7% 25% 25% 16%	2023
	21st to end	Night	22% 2 6% 26% 28% 15%	2200
October	1st to 10th	Night	16% 2 6% 20% 28% 27%	3909
	11th to 20th	Night	28% 2 11% 25% 27% 7%	3898
	21st to end	Night	27% 2 8% 30% 24% 9%	4442
November	1st to 10th	Night	27% 3 12% 26% 26% 6%	2665
	11th to 20th	Night	28% 3 9% 31% 22% 6%	2730
	21st to end	Night	29% 3 10% 31% 22% 5%	2940
December	1st to 10th	Night	25% 2 12% 37% 20% 3	4710
	11th to 20th	Night	30% 3 12% 39% 15% 1	5322
	21st to end	Night	38% 3 11% 33% 14% 2	7128

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	13% 18% 32% 26% 8% 2	330
	11th to 20th	Day	14% 20% 39% 22% 5% 1	330
	21st to end	Day	9% 22% 44% 19% 7%	363
February	1st to 10th	Day	10% 24% 42% 19% 3 1	330
	11th to 20th	Day	14% 24% 33% 25% 4	330
	21st to end	Day	20% 23% 31% 20% 6%	273
March	1st to 10th	Day	10% 23% 31% 31% 5%	330
	11th to 20th	Day	17% 17% 33% 23% 8% 1	482
	21st to end	Day	18% 16% 35% 23% 6% 2	594
April	1st to 10th	Day	19% 18% 35% 21% 7% 1	540
	11th to 20th	Day	21% 16% 38% 17% 6% 2	532
	21st to end	Day	17% 12% 32% 25% 12% 3	547
May	1st to 10th	Day	19% 11% 27% 25% 15% 4	753
	11th to 20th	Day	20% 8% 21% 29% 20% 3	775
	21st to end	Day	13% 8% 25% 32% 18% 5%	844
June	1st to 10th	Day	6% 6% 24% 30% 24% 10%	780
	11th to 20th	Day	9% 8% 28% 34% 18% 3	780
	21st to end	Day	7% 4 27% 34% 23% 5%	780
July	1st to 10th	Day	6% 2 16% 38% 28% 10%	771
	11th to 20th	Day	4 3 18% 35% 33% 7%	768
	21st to end	Day	7% 2 16% 35% 33% 8%	849
August	1st to 10th	Day	5% 3 22% 34% 28% 8%	646
	11th to 20th	Day	3 3 24% 32% 25% 12%	557
	21st to end	Day	5% 5% 23% 33% 24% 10%	620
September	1st to 10th	Day	7% 5% 22% 33% 23% 9%	530
	11th to 20th	Day	8% 6% 26% 32% 22% 7%	506
	21st to end	Day	8% 7% 22% 31% 18% 14%	330
October	1st to 10th	Day	10% 7% 22% 30% 18% 12%	330
	11th to 20th	Day	12% 15% 26% 26% 12% 7%	330
	21st to end	Day	14% 13% 33% 26% 11% 3	363
November	1st to 10th	Day	10% 12% 35% 32% 9% 2	330
	11th to 20th	Day	12% 17% 37% 25% 8% 1	330
	21st to end	Day	9% 15% 40% 26% 8% 1	330
December	1st to 10th	Day	10% 21% 40% 20% 8%	330
	11th to 20th	Day	12% 22% 45% 18% 2	330
	21st to end	Day	13% 24% 34% 23% 5% 1	363
January	1st to 10th	Night	10% 20% 40% 22% 6% 1	1050
	11th to 20th	Night	9% 24% 43% 20% 4	1050
	21st to end	Night	10% 16% 44% 27% 4	1004
February	1st to 10th	Night	9% 17% 45% 25% 4	840
	11th to 20th	Night	12% 14% 41% 29% 4	824
	21st to end	Night	11% 20% 42% 24% 4	692
March	1st to 10th	Night	12% 16% 38% 30% 4	840
	11th to 20th	Night	13% 12% 33% 35% 7%	840
	21st to end	Night	15% 11% 36% 32% 6% 1	756
April	1st to 10th	Night	14% 12% 36% 34% 4	630
	11th to 20th	Night	15% 9% 37% 33% 6%	623
	21st to end	Night	17% 7% 30% 35% 10%	630
May	1st to 10th	Night	20% 7% 24% 35% 13% 1	630
	11th to 20th	Night	17% 4 22% 39% 16% 2	621
	21st to end	Night	11% 4 28% 40% 16%	683
June	1st to 10th	Night	8% 4 26% 42% 20% 1	630
	11th to 20th	Night	9% 4 31% 47% 8%	630
	21st to end	Night	4 2 29% 49% 15% 1	630
July	1st to 10th	Night	6% 2 14% 51% 25% 1	615
	11th to 20th	Night	4 2 19% 52% 22%	612
	21st to end	Night	4 1 15% 52% 27% 1	690
August	1st to 10th	Night	7% 2 14% 54% 22% 1	627
	11th to 20th	Night	4 1 18% 54% 23%	624
	21st to end	Night	5% 2 18% 51% 24% 1	687
September	1st to 10th	Night	8% 2 18% 50% 20% 2	600
	11th to 20th	Night	9% 4 22% 46% 19% 2	600
	21st to end	Night	10% 3 26% 45% 17% 1	600
October	1st to 10th	Night	13% 5% 27% 37% 17% 2	789
	11th to 20th	Night	12% 7% 32% 39% 10% 1	800
	21st to end	Night	13% 9% 34% 35% 8% 1	995
November	1st to 10th	Night	10% 8% 40% 35% 7% 1	1025
	11th to 20th	Night	8% 17% 43% 29% 3	1050
	21st to end	Night	9% 11% 42% 32% 6%	1050
December	1st to 10th	Night	11% 21% 40% 24% 4	1050
	11th to 20th	Night	11% 19% 43% 22% 4	1050
	21st to end	Night	12% 21% 42% 22% 4	1155

Page generated at 2026-08-27 02:07:16. Version ac07

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