Prairie Grass Stargaze
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prairie Grass Stargaze clear sky chart from 2005-11-05 to 2024-10-14.

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% 8% 3 7% 5% 4 4 4 5% 7% 39%	101954
	Night	11% 8% 3 8% 5% 4 4 4 5% 6% 41%	96696
Transparency	Day	43% 7% 14% 24% 12% 1	101749
	Night	42% 7% 13% 23% 13% 2	96577
Seeing	Day	16% 10% 32% 27% 13% 3	15908
	Night	14% 10% 35% 30% 10% 1	25741

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	9% 15% 6% 20% 10% 6% 3 3 4 4 21%	2527
	11th to 20th	Day	6% 14% 5% 10% 7% 5% 10% 5% 9% 6% 23%	2821
	21st to end	Day	5% 15% 11% 13% 7% 5% 5% 4 5% 6% 24%	3135
February	1st to 10th	Day	7% 12% 3 10% 9% 7% 7% 6% 6% 6% 26%	1710
	11th to 20th	Day	9% 11% 4 10% 7% 7% 6% 4 6% 6% 30%	1664
	21st to end	Day	13% 11% 3 10% 7% 4 5% 4 6% 6% 31%	1489
March	1st to 10th	Day	14% 9% 4 7% 5% 4 4 3 5% 7% 38%	3418
	11th to 20th	Day	11% 11% 3 8% 4 4 4 3 5% 7% 41%	3480
	21st to end	Day	25% 14% 6% 10% 4 3 3 3 4 5% 23%	3814
April	1st to 10th	Day	18% 9% 3 6% 4 4 5% 3 6% 7% 35%	2215
	11th to 20th	Day	20% 10% 4 7% 4 4 4 3 4 6% 34%	2361
	21st to end	Day	23% 11% 3 6% 4 4 4 3 4 5% 33%	2470
May	1st to 10th	Day	17% 7% 2 5% 4 4 5% 4 7% 8% 37%	4082
	11th to 20th	Day	15% 6% 2 6% 4 4 4 3 5% 6% 45%	4321
	21st to end	Day	18% 6% 2 6% 4 4 4 4 6% 7% 38%	4824
June	1st to 10th	Day	12% 5% 2 4 4 4 4 3 6% 8% 48%	2660
	11th to 20th	Day	15% 5% 2 6% 5% 4 4 4 6% 8% 40%	2813
	21st to end	Day	10% 5% 2 6% 4 4 4 4 7% 9% 45%	2850
July	1st to 10th	Day	9% 5% 2 6% 5% 4 6% 5% 7% 9% 41%	4750
	11th to 20th	Day	5% 3 2 4 3 3 4 4 5% 8% 58%	4450
	21st to end	Day	5% 4 2 4 4 4 5% 4 6% 9% 53%	4465
August	1st to 10th	Day	13% 6% 3 6% 4 4 5% 4 5% 6% 43%	4104
	11th to 20th	Day	13% 7% 2 6% 5% 4 5% 5% 7% 8% 39%	4041
	21st to end	Day	9% 4 2 5% 4 4 4 3 6% 8% 52%	4446
September	1st to 10th	Day	11% 5% 1 4 4 4 4 4 4 7% 51%	2280
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 4 7% 51%	2120
	21st to end	Day	13% 5% 2 5% 3 3 4 4 5% 7% 49%	2081
October	1st to 10th	Day	15% 7% 2 5% 3 4 4 2 4 6% 47%	1900
	11th to 20th	Day	14% 9% 2 6% 4 4 4 3 4 5% 46%	1830
	21st to end	Day	17% 8% 3 8% 4 3 3 3 4 6% 43%	1976
November	1st to 10th	Day	12% 8% 2 7% 3 4 3 4 5% 7% 43%	1596
	11th to 20th	Day	11% 11% 4 12% 6% 5% 4 3 5% 5% 35%	1520
	21st to end	Day	12% 10% 4 8% 5% 5% 3 3 6% 6% 38%	1520
December	1st to 10th	Day	11% 11% 5% 9% 9% 6% 4 4 6% 6% 30%	1520
	11th to 20th	Day	11% 12% 6% 10% 6% 4 3 4 5% 8% 31%	1918
	21st to end	Day	18% 11% 4 18% 4 4 4 3 5% 7% 22%	2783
January	1st to 10th	Night	9% 12% 5% 17% 11% 6% 4 4 4 5% 23%	4428
	11th to 20th	Night	5% 10% 5% 14% 8% 7% 10% 6% 7% 7% 21%	4148
	21st to end	Night	7% 15% 10% 14% 5% 5% 4 3 4 5% 27%	4532
February	1st to 10th	Night	8% 12% 4 10% 7% 5% 5% 5% 4 6% 33%	2470
	11th to 20th	Night	9% 9% 4 8% 6% 5% 6% 5% 6% 6% 37%	2403
	21st to end	Night	10% 9% 3 9% 6% 5% 5% 4 5% 7% 36%	1983
March	1st to 10th	Night	9% 8% 3 7% 4 3 3 3 4 6% 49%	3435
	11th to 20th	Night	10% 7% 2 6% 5% 4 5% 4 6% 6% 43%	3480
	21st to end	Night	28% 11% 4 9% 4 3 3 2 3 5% 27%	3817
April	1st to 10th	Night	15% 10% 3 6% 4 3 4 4 6% 6% 39%	1964
	11th to 20th	Night	17% 10% 4 6% 4 3 4 3 5% 5% 40%	1766
	21st to end	Night	18% 8% 3 6% 3 3 4 3 5% 7% 39%	1710
May	1st to 10th	Night	17% 6% 2 5% 3 3 4 3 5% 6% 45%	2823
	11th to 20th	Night	12% 5% 2 5% 4 4 4 3 5% 7% 50%	2583
	21st to end	Night	17% 6% 2 5% 3 4 3 3 5% 6% 45%	2743
June	1st to 10th	Night	8% 4 1 3 3 3 4 4 6% 8% 55%	1520
	11th to 20th	Night	10% 4 2 4 4 3 5% 5% 6% 8% 48%	1361
	21st to end	Night	7% 3 2 4 3 3 4 3 6% 7% 58%	1330
July	1st to 10th	Night	9% 4 1 5% 4 4 5% 4 7% 9% 47%	2220
	11th to 20th	Night	3 2 1 3 2 4 4 3 6% 7% 64%	2511
	21st to end	Night	4 3 1 4 3 3 4 3 6% 9% 59%	3098
August	1st to 10th	Night	13% 5% 2 4 3 3 4 3 5% 7% 51%	2836
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 6% 8% 52%	2798
	21st to end	Night	8% 4 2 5% 4 3 4 3 5% 8% 53%	3217
September	1st to 10th	Night	9% 4 2 5% 3 2 4 2 4 7% 59%	1900
	11th to 20th	Night	9% 4 2 4 3 4 3 3 5% 7% 56%	2057
	21st to end	Night	11% 4 2 4 2 3 4 3 5% 7% 55%	2090
October	1st to 10th	Night	14% 5% 2 4 3 3 3 3 4 6% 51%	2270
	11th to 20th	Night	14% 9% 2 6% 3 3 3 3 4 6% 47%	2203
	21st to end	Night	15% 10% 3 7% 3 3 3 3 4 6% 44%	2376
November	1st to 10th	Night	11% 7% 2 7% 5% 5% 4 4 5% 5% 47%	2481
	11th to 20th	Night	10% 10% 3 9% 5% 5% 4 4 4 5% 40%	2660
	21st to end	Night	12% 8% 3 8% 4 4 4 4 5% 6% 41%	2660
December	1st to 10th	Night	8% 11% 5% 11% 7% 4 5% 4 5% 6% 34%	2660
	11th to 20th	Night	11% 10% 5% 10% 6% 5% 5% 4 5% 7% 31%	3279
	21st to end	Night	18% 12% 5% 13% 5% 5% 5% 4 5% 5% 24%	4884

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	66% 5% 10% 14% 4	2528
	11th to 20th	Day	56% 6% 10% 21% 6%	2821
	21st to end	Day	59% 7% 14% 15% 5%	3135
February	1st to 10th	Day	55% 7% 15% 15% 8% 1	1710
	11th to 20th	Day	53% 7% 13% 18% 7% 2	1673
	21st to end	Day	50% 8% 12% 17% 11% 2	1489
March	1st to 10th	Day	45% 6% 13% 24% 10% 1	3418
	11th to 20th	Day	41% 7% 11% 26% 12% 3	3480
	21st to end	Day	63% 7% 11% 13% 6% 1	3814
April	1st to 10th	Day	47% 6% 15% 21% 9% 1	2215
	11th to 20th	Day	51% 6% 12% 19% 11% 1	2361
	21st to end	Day	52% 6% 11% 21% 9%	2470
May	1st to 10th	Day	41% 9% 14% 22% 13%	4120
	11th to 20th	Day	37% 7% 12% 26% 15% 3	4325
	21st to end	Day	42% 9% 13% 25% 11% 1	4837
June	1st to 10th	Day	34% 8% 16% 27% 14% 1	2660
	11th to 20th	Day	41% 8% 13% 21% 15% 2	2813
	21st to end	Day	35% 8% 15% 27% 13% 2	2850
July	1st to 10th	Day	36% 9% 21% 23% 11% 1	4676
	11th to 20th	Day	23% 7% 15% 34% 18% 3	4373
	21st to end	Day	27% 8% 17% 29% 18% 1	4325
August	1st to 10th	Day	40% 7% 11% 28% 12% 2	4090
	11th to 20th	Day	40% 9% 15% 28% 8% 1	4080
	21st to end	Day	31% 6% 18% 28% 15% 2	4445
September	1st to 10th	Day	33% 6% 13% 30% 18% 1	2280
	11th to 20th	Day	32% 6% 17% 30% 14% 1	2120
	21st to end	Day	34% 6% 11% 31% 16% 1	2081
October	1st to 10th	Day	39% 5% 12% 28% 16% 1	1900
	11th to 20th	Day	40% 5% 12% 27% 14% 2	1830
	21st to end	Day	44% 5% 13% 24% 13% 1	1976
November	1st to 10th	Day	40% 5% 15% 21% 16% 4	1596
	11th to 20th	Day	50% 6% 12% 20% 11%	1520
	21st to end	Day	46% 6% 17% 19% 11% 1	1520
December	1st to 10th	Day	54% 6% 15% 15% 9% 1	1520
	11th to 20th	Day	52% 6% 18% 18% 6%	1915
	21st to end	Day	61% 7% 12% 14% 6% 1	2783
January	1st to 10th	Night	62% 6% 9% 16% 6%	4428
	11th to 20th	Night	57% 7% 13% 16% 7%	4148
	21st to end	Night	58% 7% 12% 15% 8%	4532
February	1st to 10th	Night	50% 7% 12% 21% 9% 2	2470
	11th to 20th	Night	44% 7% 14% 20% 13% 2	2404
	21st to end	Night	45% 7% 13% 20% 11% 3	1983
March	1st to 10th	Night	37% 5% 11% 29% 16% 1	3435
	11th to 20th	Night	36% 7% 12% 29% 15% 1	3480
	21st to end	Night	62% 5% 12% 14% 6% 1	3817
April	1st to 10th	Night	43% 8% 13% 24% 11% 1	1964
	11th to 20th	Night	45% 6% 10% 21% 17% 2	1766
	21st to end	Night	43% 7% 10% 25% 13% 2	1710
May	1st to 10th	Night	39% 7% 13% 20% 20% 2	2850
	11th to 20th	Night	32% 8% 11% 26% 18% 5%	2584
	21st to end	Night	38% 7% 12% 25% 15% 2	2751
June	1st to 10th	Night	27% 8% 18% 27% 17% 3	1520
	11th to 20th	Night	31% 9% 16% 22% 19% 3	1361
	21st to end	Night	24% 7% 17% 32% 19% 2	1330
July	1st to 10th	Night	31% 7% 22% 24% 13% 2	2185
	11th to 20th	Night	18% 6% 14% 36% 22% 3	2465
	21st to end	Night	21% 8% 17% 32% 20% 2	2999
August	1st to 10th	Night	34% 5% 14% 27% 17% 3	2826
	11th to 20th	Night	32% 6% 15% 33% 12% 1	2825
	21st to end	Night	29% 7% 18% 27% 17% 2	3217
September	1st to 10th	Night	26% 4 14% 32% 22% 2	1900
	11th to 20th	Night	28% 6% 15% 33% 17% 2	2057
	21st to end	Night	29% 6% 12% 30% 22% 2	2090
October	1st to 10th	Night	34% 5% 11% 28% 20% 2	2270
	11th to 20th	Night	38% 4 12% 26% 17% 3	2208
	21st to end	Night	42% 5% 14% 23% 15% 1	2376
November	1st to 10th	Night	38% 5% 15% 21% 18% 3	2481
	11th to 20th	Night	46% 7% 12% 21% 13% 2	2660
	21st to end	Night	42% 6% 16% 22% 12% 1	2660
December	1st to 10th	Night	49% 7% 15% 20% 9%	2660
	11th to 20th	Night	50% 8% 18% 18% 6%	3281
	21st to end	Night	60% 7% 10% 17% 5% 1	4884

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	14% 13% 37% 23% 10% 3	270
	11th to 20th	Day	19% 13% 37% 24% 5% 1	270
	21st to end	Day	13% 12% 39% 25% 10% 1	297
February	1st to 10th	Day	14% 17% 44% 22% 4	270
	11th to 20th	Day	14% 16% 41% 23% 5% 1	270
	21st to end	Day	19% 16% 41% 21% 3	225
March	1st to 10th	Day	20% 15% 40% 21% 3	270
	11th to 20th	Day	22% 11% 37% 21% 8% 1	270
	21st to end	Day	27% 14% 29% 21% 7% 1	297
April	1st to 10th	Day	26% 16% 34% 18% 6%	395
	11th to 20th	Day	26% 15% 31% 21% 6% 1	559
	21st to end	Day	26% 16% 27% 20% 9% 2	650
May	1st to 10th	Day	21% 14% 32% 23% 8% 2	653
	11th to 20th	Day	21% 11% 30% 24% 12% 3	675
	21st to end	Day	17% 10% 29% 29% 13% 2	734
June	1st to 10th	Day	10% 8% 27% 31% 20% 5%	680
	11th to 20th	Day	15% 8% 35% 28% 11% 3	680
	21st to end	Day	10% 9% 32% 32% 15% 2	680
July	1st to 10th	Day	7% 6% 23% 33% 26% 6%	671
	11th to 20th	Day	7% 4 32% 31% 20% 7%	668
	21st to end	Day	6% 3 25% 40% 20% 5%	739
August	1st to 10th	Day	11% 5% 21% 37% 22% 5%	676
	11th to 20th	Day	13% 4 24% 33% 22% 5%	665
	21st to end	Day	8% 5% 30% 34% 18% 5%	701
September	1st to 10th	Day	15% 6% 29% 28% 19% 3	490
	11th to 20th	Day	9% 6% 34% 34% 14% 3	330
	21st to end	Day	16% 13% 32% 20% 14% 5%	300
October	1st to 10th	Day	20% 10% 31% 22% 13% 4	300
	11th to 20th	Day	15% 17% 40% 19% 8% 1	279
	21st to end	Day	23% 18% 36% 18% 6%	297
November	1st to 10th	Day	21% 13% 33% 23% 6% 3	270
	11th to 20th	Day	15% 23% 40% 18% 4	270
	21st to end	Day	20% 15% 39% 20% 5%	270
December	1st to 10th	Day	13% 12% 44% 22% 9%	270
	11th to 20th	Day	16% 14% 41% 22% 6%	270
	21st to end	Day	26% 16% 37% 19% 2	297
January	1st to 10th	Night	12% 12% 45% 24% 7% 1	950
	11th to 20th	Night	12% 13% 41% 27% 5% 1	950
	21st to end	Night	17% 14% 38% 26% 5%	1045
February	1st to 10th	Night	14% 13% 43% 25% 5% 1	950
	11th to 20th	Night	13% 16% 41% 24% 6%	929
	21st to end	Night	14% 12% 41% 24% 8% 2	727
March	1st to 10th	Night	14% 12% 42% 24% 8%	586
	11th to 20th	Night	16% 13% 40% 25% 6%	570
	21st to end	Night	24% 11% 28% 27% 9% 1	627
April	1st to 10th	Night	20% 13% 40% 23% 4	570
	11th to 20th	Night	21% 13% 35% 24% 7% 1	563
	21st to end	Night	20% 12% 34% 25% 8% 1	570
May	1st to 10th	Night	17% 10% 36% 29% 7%	570
	11th to 20th	Night	18% 8% 33% 30% 9% 1	561
	21st to end	Night	17% 8% 30% 33% 11%	617
June	1st to 10th	Night	9% 6% 29% 42% 14% 1	570
	11th to 20th	Night	11% 5% 34% 40% 10%	570
	21st to end	Night	9% 4 26% 48% 13%	570
July	1st to 10th	Night	6% 2 26% 39% 26% 1	555
	11th to 20th	Night	2 2 29% 43% 22% 1	552
	21st to end	Night	4 1 25% 48% 20% 2	624
August	1st to 10th	Night	8% 2 21% 45% 21% 1	567
	11th to 20th	Night	8% 4 23% 41% 21% 3	564
	21st to end	Night	8% 3 27% 40% 19% 2	627
September	1st to 10th	Night	10% 4 28% 42% 15% 2	570
	11th to 20th	Night	10% 5% 34% 37% 13% 2	570
	21st to end	Night	11% 11% 33% 31% 13% 1	570
October	1st to 10th	Night	17% 9% 32% 31% 10% 1	750
	11th to 20th	Night	16% 14% 36% 26% 7%	735
	21st to end	Night	21% 13% 31% 27% 7%	792
November	1st to 10th	Night	14% 13% 37% 26% 9%	925
	11th to 20th	Night	15% 14% 41% 23% 6% 1	950
	21st to end	Night	15% 14% 41% 24% 6%	950
December	1st to 10th	Night	14% 12% 42% 26% 6%	950
	11th to 20th	Night	19% 11% 38% 25% 6% 1	950
	21st to end	Night	22% 14% 37% 22% 4	1045

Page generated at 2024-10-11 09:49:59. Version ac07

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