Prairie Golf Association
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prairie Golf Association clear sky chart from 2005-11-06 to 2025-10-19.

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	10% 6% 2 6% 4 4 4 3 5% 7% 48%	135876
	Night	8% 6% 2 6% 4 3 4 3 5% 7% 51%	131135
Transparency	Day	35% 6% 12% 26% 18% 3	130585
	Night	33% 5% 12% 26% 20% 4	127434
Seeing	Day	13% 9% 31% 30% 13% 2	17114
	Night	12% 9% 36% 34% 9%	26929

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	9% 13% 5% 11% 6% 5% 4 4 4 5% 34%	3638
	11th to 20th	Day	5% 9% 4 8% 5% 4 5% 4 4 6% 46%	4010
	21st to end	Day	5% 7% 3 12% 5% 5% 4 3 4 5% 47%	4488
February	1st to 10th	Day	9% 11% 4 8% 5% 4 5% 4 5% 7% 39%	1800
	11th to 20th	Day	6% 9% 4 8% 4 4 4 4 5% 7% 45%	1919
	21st to end	Day	8% 8% 3 5% 4 4 4 3 5% 5% 51%	1650
March	1st to 10th	Day	12% 8% 3 5% 3 2 3 2 3 4 55%	4662
	11th to 20th	Day	10% 7% 2 5% 3 3 3 3 4 6% 54%	4980
	21st to end	Day	15% 11% 3 8% 4 4 4 4 5% 7% 36%	5464
April	1st to 10th	Day	12% 7% 3 5% 4 3 3 3 5% 7% 47%	2266
	11th to 20th	Day	14% 8% 2 5% 4 4 3 3 5% 7% 44%	2524
	21st to end	Day	19% 7% 2 6% 4 4 4 3 5% 7% 40%	2600
May	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 6% 8% 48%	5900
	11th to 20th	Day	12% 5% 2 5% 3 3 3 3 4 7% 52%	5862
	21st to end	Day	18% 7% 3 7% 4 4 4 4 5% 6% 39%	6446
June	1st to 10th	Day	7% 4 2 4 4 4 5% 4 6% 9% 53%	2613
	11th to 20th	Day	9% 5% 1 4 4 5% 4 4 6% 8% 51%	2800
	21st to end	Day	6% 3 2 4 4 3 5% 4 7% 9% 53%	2800
July	1st to 10th	Day	9% 5% 2 6% 4 4 4 3 6% 8% 49%	6339
	11th to 20th	Day	6% 5% 2 6% 4 5% 5% 4 7% 8% 48%	6120
	21st to end	Day	7% 5% 2 6% 4 4 4 4 6% 9% 49%	6424
August	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 4 7% 9% 44%	5801
	11th to 20th	Day	9% 5% 2 6% 4 4 4 4 7% 10% 46%	5821
	21st to end	Day	11% 5% 2 7% 4 4 4 3 5% 7% 47%	6380
September	1st to 10th	Day	12% 5% 2 5% 3 3 3 2 4 5% 55%	2251
	11th to 20th	Day	9% 4 1 5% 3 4 4 3 4 7% 56%	2200
	21st to end	Day	10% 4 1 4 3 2 3 3 4 6% 61%	2200
October	1st to 10th	Day	8% 4 1 3 2 2 2 2 3 4 70%	3498
	11th to 20th	Day	7% 3 1 3 3 2 3 3 5% 6% 64%	3220
	21st to end	Day	10% 5% 2 4 3 3 3 3 5% 7% 55%	3255
November	1st to 10th	Day	7% 6% 2 5% 3 4 4 4 5% 7% 54%	1763
	11th to 20th	Day	8% 7% 2 5% 4 3 2 4 4 6% 56%	1800
	21st to end	Day	10% 8% 2 6% 4 3 3 3 6% 6% 49%	1800
December	1st to 10th	Day	5% 4 2 6% 4 4 4 4 5% 6% 56%	2940
	11th to 20th	Day	5% 9% 3 7% 5% 5% 5% 3 6% 7% 46%	3391
	21st to end	Day	13% 10% 3 12% 4 4 4 3 4 6% 38%	4251
January	1st to 10th	Night	8% 13% 4 12% 5% 4 5% 4 6% 6% 33%	6327
	11th to 20th	Night	4 7% 3 7% 4 4 6% 4 5% 6% 49%	5962
	21st to end	Night	5% 8% 4 12% 4 4 4 3 5% 5% 45%	6490
February	1st to 10th	Night	8% 11% 4 8% 6% 4 4 4 5% 5% 42%	2600
	11th to 20th	Night	7% 9% 3 7% 5% 5% 5% 4 5% 6% 44%	2386
	21st to end	Night	7% 7% 2 6% 3 4 4 3 5% 6% 54%	1980
March	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 5% 5% 55%	5202
	11th to 20th	Night	10% 6% 1 4 3 3 3 2 5% 6% 58%	4980
	21st to end	Night	12% 10% 3 6% 4 4 4 4 6% 8% 39%	5467
April	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 6% 7% 47%	2130
	11th to 20th	Night	12% 6% 2 5% 4 3 5% 3 6% 9% 45%	1824
	21st to end	Night	16% 5% 2 5% 4 3 3 3 5% 7% 47%	1800
May	1st to 10th	Night	14% 7% 1 4 4 3 4 3 5% 7% 48%	4080
	11th to 20th	Night	11% 6% 2 4 3 3 3 3 6% 8% 53%	4053
	21st to end	Night	16% 6% 2 6% 4 3 4 3 6% 7% 43%	4451
June	1st to 10th	Night	7% 4 2 4 3 4 4 4 7% 10% 53%	1780
	11th to 20th	Night	7% 5% 2 5% 3 3 3 3 6% 8% 55%	1600
	21st to end	Night	4 4 1 5% 4 4 4 4 6% 9% 56%	1600
July	1st to 10th	Night	7% 5% 2 6% 3 3 3 3 5% 8% 55%	3640
	11th to 20th	Night	7% 5% 2 6% 4 5% 4 5% 7% 9% 46%	3855
	21st to end	Night	5% 5% 2 5% 4 3 4 4 6% 8% 56%	4449
August	1st to 10th	Night	4 3 2 4 3 4 5% 5% 7% 13% 51%	4011
	11th to 20th	Night	7% 4 1 4 4 3 4 4 6% 11% 51%	4028
	21st to end	Night	9% 4 2 5% 4 4 5% 4 7% 8% 48%	4579
September	1st to 10th	Night	8% 3 1 4 3 2 3 3 4 6% 62%	2148
	11th to 20th	Night	7% 4 2 4 4 3 3 3 5% 7% 58%	2200
	21st to end	Night	7% 3 2 4 4 3 3 4 5% 6% 60%	2200
October	1st to 10th	Night	9% 3 1 3 2 2 2 2 3 5% 70%	3648
	11th to 20th	Night	6% 3 1 4 3 3 3 2 4 6% 65%	3876
	21st to end	Night	9% 4 1 4 3 2 3 2 4 7% 58%	4295
November	1st to 10th	Night	6% 5% 2 3 3 3 3 3 5% 7% 60%	2535
	11th to 20th	Night	8% 6% 2 4 3 4 3 3 4 6% 57%	2600
	21st to end	Night	9% 6% 2 5% 2 3 3 3 5% 7% 54%	2600
December	1st to 10th	Night	4 5% 2 4 3 3 4 3 5% 7% 60%	4250
	11th to 20th	Night	7% 5% 2 6% 4 4 4 4 6% 8% 50%	4816
	21st to end	Night	13% 11% 3 10% 4 3 4 3 4 6% 38%	6693

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	51% 6% 10% 22% 11% 1	3639
	11th to 20th	Day	39% 6% 14% 20% 19% 3	4010
	21st to end	Day	40% 5% 12% 26% 14% 3	4488
February	1st to 10th	Day	45% 7% 15% 21% 11% 2	1800
	11th to 20th	Day	38% 5% 15% 22% 16% 4	1929
	21st to end	Day	35% 5% 12% 26% 17% 5%	1650
March	1st to 10th	Day	34% 4 8% 24% 24% 7%	4662
	11th to 20th	Day	33% 4 7% 24% 25% 7%	4980
	21st to end	Day	45% 7% 20% 20% 6% 2	5464
April	1st to 10th	Day	37% 5% 14% 26% 15% 2	2266
	11th to 20th	Day	40% 5% 14% 23% 15% 3	2527
	21st to end	Day	44% 6% 11% 24% 14% 1	2600
May	1st to 10th	Day	33% 6% 12% 25% 21% 3	5900
	11th to 20th	Day	32% 6% 11% 24% 19% 7%	5866
	21st to end	Day	44% 6% 9% 27% 13% 1	6447
June	1st to 10th	Day	26% 8% 17% 32% 15% 2	2613
	11th to 20th	Day	31% 6% 14% 28% 18% 3	2800
	21st to end	Day	26% 8% 14% 30% 18% 4	2800
July	1st to 10th	Day	32% 6% 12% 30% 19% 1	6271
	11th to 20th	Day	31% 8% 13% 29% 17% 2	6046
	21st to end	Day	30% 8% 15% 26% 18% 4	6240
August	1st to 10th	Day	34% 8% 15% 25% 14% 4	4220
	11th to 20th	Day	38% 7% 14% 24% 17% 1	4210
	21st to end	Day	28% 6% 14% 24% 22% 7%	4590
September	1st to 10th	Day	32% 5% 13% 24% 20% 6%	2251
	11th to 20th	Day	29% 5% 12% 31% 21% 2	2200
	21st to end	Day	25% 4 9% 33% 27% 2	2200
October	1st to 10th	Day	21% 3 5% 21% 43% 7%	3498
	11th to 20th	Day	22% 4 10% 35% 21% 9%	3220
	21st to end	Day	30% 3 10% 31% 23% 3	3255
November	1st to 10th	Day	29% 4 14% 29% 21% 3	1763
	11th to 20th	Day	30% 4 11% 28% 24% 3	1800
	21st to end	Day	36% 4 12% 27% 18% 3	1800
December	1st to 10th	Day	29% 4 14% 31% 20% 3	2940
	11th to 20th	Day	37% 5% 18% 27% 13% 1	3389
	21st to end	Day	49% 4 9% 26% 11% 1	4251
January	1st to 10th	Night	49% 6% 9% 22% 14% 1	6327
	11th to 20th	Night	34% 4 13% 26% 19% 3	5962
	21st to end	Night	41% 5% 10% 21% 20% 3	6490
February	1st to 10th	Night	43% 5% 12% 23% 14% 3	2600
	11th to 20th	Night	39% 6% 13% 24% 15% 3	2386
	21st to end	Night	32% 4 11% 23% 23% 7%	1980
March	1st to 10th	Night	31% 3 7% 27% 25% 6%	5202
	11th to 20th	Night	28% 3 6% 21% 32% 9%	4980
	21st to end	Night	42% 7% 18% 25% 8% 1	5467
April	1st to 10th	Night	36% 5% 13% 25% 19% 2	2130
	11th to 20th	Night	36% 6% 13% 27% 15% 3	1824
	21st to end	Night	37% 6% 12% 26% 17% 2	1800
May	1st to 10th	Night	35% 5% 11% 29% 19% 2	4080
	11th to 20th	Night	30% 7% 13% 23% 22% 6%	4054
	21st to end	Night	38% 9% 13% 23% 16% 1	4452
June	1st to 10th	Night	25% 8% 18% 29% 17% 2	1780
	11th to 20th	Night	27% 6% 14% 29% 18% 6%	1600
	21st to end	Night	23% 6% 16% 31% 21% 3	1600
July	1st to 10th	Night	28% 6% 13% 34% 16% 3	3600
	11th to 20th	Night	32% 8% 14% 28% 16% 2	3807
	21st to end	Night	25% 7% 16% 25% 23% 4	4320
August	1st to 10th	Night	24% 8% 19% 28% 17% 5%	2916
	11th to 20th	Night	33% 6% 17% 28% 15% 1	2915
	21st to end	Night	24% 6% 15% 29% 17% 9%	3300
September	1st to 10th	Night	24% 4 11% 28% 24% 9%	2148
	11th to 20th	Night	26% 4 12% 31% 24% 4	2200
	21st to end	Night	26% 5% 8% 27% 29% 5%	2200
October	1st to 10th	Night	20% 3 6% 17% 46% 8%	3648
	11th to 20th	Night	22% 3 10% 29% 26% 10%	3876
	21st to end	Night	27% 3 10% 29% 27% 4	4295
November	1st to 10th	Night	23% 4 13% 29% 25% 6%	2535
	11th to 20th	Night	29% 4 10% 29% 24% 5%	2600
	21st to end	Night	30% 4 13% 28% 22% 3	2600
December	1st to 10th	Night	24% 4 15% 35% 20% 2	4250
	11th to 20th	Night	31% 4 15% 33% 16% 1	4817
	21st to end	Night	48% 4 10% 25% 11% 1	6693

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	17% 13% 37% 23% 8% 2	300
	11th to 20th	Day	16% 16% 34% 27% 7% 1	300
	21st to end	Day	13% 9% 48% 22% 7% 1	330
February	1st to 10th	Day	14% 15% 45% 23% 3	300
	11th to 20th	Day	13% 10% 47% 23% 6% 1	300
	21st to end	Day	12% 18% 47% 18% 4	249
March	1st to 10th	Day	14% 14% 43% 25% 4 1	300
	11th to 20th	Day	20% 11% 38% 21% 9%	300
	21st to end	Day	26% 16% 38% 16% 4	330
April	1st to 10th	Day	19% 22% 38% 18% 3	366
	11th to 20th	Day	19% 17% 36% 22% 5%	645
	21st to end	Day	23% 16% 31% 19% 8% 2	700
May	1st to 10th	Day	16% 12% 33% 27% 11% 2	703
	11th to 20th	Day	19% 12% 29% 24% 13% 3	725
	21st to end	Day	17% 9% 31% 29% 12% 1	789
June	1st to 10th	Day	7% 7% 26% 35% 21% 5%	730
	11th to 20th	Day	11% 5% 32% 33% 15% 3	730
	21st to end	Day	8% 7% 33% 34% 17% 2	730
July	1st to 10th	Day	9% 3 20% 38% 25% 5%	721
	11th to 20th	Day	5% 2 21% 45% 22% 4	718
	21st to end	Day	8% 3 20% 42% 24% 4	794
August	1st to 10th	Day	7% 3 20% 46% 21% 3	726
	11th to 20th	Day	7% 5% 20% 42% 24% 2	715
	21st to end	Day	11% 3 22% 39% 21% 4	758
September	1st to 10th	Day	12% 4 28% 36% 16% 3	381
	11th to 20th	Day	7% 7% 29% 37% 15% 5%	330
	21st to end	Day	15% 8% 28% 28% 15% 6%	330
October	1st to 10th	Day	19% 8% 27% 32% 11% 4	330
	11th to 20th	Day	13% 14% 39% 24% 9% 1	324
	21st to end	Day	18% 16% 34% 24% 7% 1	330
November	1st to 10th	Day	15% 14% 40% 20% 9% 2	300
	11th to 20th	Day	12% 16% 45% 20% 6%	300
	21st to end	Day	19% 15% 36% 20% 9% 1	300
December	1st to 10th	Day	9% 11% 43% 31% 5% 1	300
	11th to 20th	Day	15% 9% 44% 27% 5%	300
	21st to end	Day	19% 12% 44% 22% 3	330
January	1st to 10th	Night	12% 12% 36% 33% 6% 1	1000
	11th to 20th	Night	11% 12% 41% 29% 5% 1	1000
	21st to end	Night	11% 9% 43% 31% 6%	1100
February	1st to 10th	Night	13% 13% 42% 28% 4	1000
	11th to 20th	Night	12% 12% 42% 30% 5%	832
	21st to end	Night	10% 12% 46% 26% 5%	660
March	1st to 10th	Night	13% 13% 42% 29% 4	732
	11th to 20th	Night	16% 10% 41% 28% 5%	600
	21st to end	Night	19% 12% 41% 24% 4	660
April	1st to 10th	Night	18% 14% 43% 24% 3	600
	11th to 20th	Night	16% 15% 41% 24% 3 1	593
	21st to end	Night	20% 11% 33% 29% 7% 1	600
May	1st to 10th	Night	18% 9% 33% 33% 8%	600
	11th to 20th	Night	14% 9% 36% 32% 9% 1	591
	21st to end	Night	16% 7% 34% 32% 11% 1	650
June	1st to 10th	Night	8% 5% 28% 44% 14% 2	600
	11th to 20th	Night	8% 6% 37% 38% 11%	600
	21st to end	Night	5% 4 36% 41% 14%	600
July	1st to 10th	Night	6% 3 22% 44% 25% 1	585
	11th to 20th	Night	3 2 21% 52% 21% 1	582
	21st to end	Night	5% 2 19% 55% 20%	657
August	1st to 10th	Night	5% 2 22% 48% 20% 2	597
	11th to 20th	Night	7% 2 24% 48% 19%	594
	21st to end	Night	8% 3 25% 43% 20% 2	660
September	1st to 10th	Night	9% 3 28% 44% 16% 1	600
	11th to 20th	Night	9% 4 34% 39% 13% 1	600
	21st to end	Night	8% 7% 34% 34% 16% 1	600
October	1st to 10th	Night	16% 9% 30% 34% 12%	632
	11th to 20th	Night	12% 12% 38% 31% 7%	793
	21st to end	Night	15% 12% 33% 30% 10%	936
November	1st to 10th	Night	8% 10% 37% 38% 6% 1	975
	11th to 20th	Night	11% 12% 40% 31% 6%	1000
	21st to end	Night	12% 11% 37% 31% 10%	1000
December	1st to 10th	Night	10% 11% 44% 30% 4	1000
	11th to 20th	Night	13% 10% 42% 30% 6%	1000
	21st to end	Night	17% 11% 38% 28% 5%	1100

Page generated at 2025-10-16 00:50:30. Version ac07

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