Maple Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Maple Creek clear sky chart from 2005-11-06 to 2026-07-01.

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	8% 8% 3 7% 4 4 5% 4 6% 8% 43%	146999
	Night	7% 9% 3 8% 5% 4 5% 4 6% 7% 42%	142693
Transparency	Day	38% 7% 15% 25% 12% 2	141598
	Night	40% 7% 16% 24% 12% 2	139106
Seeing	Day	12% 10% 29% 29% 16% 4	17823
	Night	12% 10% 33% 32% 12% 1	27102

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	5% 12% 6% 13% 7% 5% 5% 4 6% 8% 29%	4124
	11th to 20th	Day	4 9% 4 11% 5% 6% 8% 5% 6% 7% 34%	4140
	21st to end	Day	3 9% 5% 9% 6% 5% 4 3 5% 6% 44%	4983
February	1st to 10th	Day	7% 13% 5% 11% 7% 6% 7% 4 4 7% 29%	1890
	11th to 20th	Day	8% 13% 6% 9% 5% 6% 6% 5% 6% 6% 30%	1845
	21st to end	Day	4 11% 4 14% 7% 5% 5% 5% 5% 6% 33%	1557
March	1st to 10th	Day	4 10% 4 10% 6% 4 4 3 5% 7% 42%	4819
	11th to 20th	Day	5% 9% 4 10% 5% 5% 5% 3 6% 9% 37%	5110
	21st to end	Day	6% 17% 6% 13% 5% 5% 4 5% 6% 7% 26%	5640
April	1st to 10th	Day	8% 10% 3 7% 6% 5% 5% 4 7% 7% 37%	2520
	11th to 20th	Day	10% 14% 4 9% 5% 4 5% 4 6% 8% 31%	2690
	21st to end	Day	12% 11% 4 7% 4 4 4 4 6% 7% 38%	2740
May	1st to 10th	Day	11% 9% 3 7% 4 5% 5% 4 5% 7% 41%	8224
	11th to 20th	Day	13% 9% 3 8% 6% 6% 6% 5% 7% 8% 30%	8191
	21st to end	Day	10% 6% 2 6% 4 5% 5% 4 6% 9% 43%	9608
June	1st to 10th	Day	14% 6% 2 6% 5% 4 5% 4 6% 8% 38%	3150
	11th to 20th	Day	17% 7% 2 6% 5% 5% 5% 4 6% 8% 35%	3150
	21st to end	Day	9% 4 1 5% 3 5% 6% 4 6% 9% 47%	3150
July	1st to 10th	Day	7% 4 1 5% 4 4 4 4 6% 8% 54%	6780
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 6% 8% 51%	6780
	21st to end	Day	7% 4 1 3 3 3 3 3 5% 7% 62%	7305
August	1st to 10th	Day	9% 5% 2 6% 4 4 4 4 6% 8% 48%	6055
	11th to 20th	Day	4 3 1 4 3 4 5% 4 7% 10% 54%	5798
	21st to end	Day	8% 3 1 3 2 2 3 2 3 6% 65%	6468
September	1st to 10th	Day	10% 5% 2 5% 3 4 3 4 4 6% 52%	2406
	11th to 20th	Day	13% 6% 1 4 3 4 4 3 5% 8% 49%	2320
	21st to end	Day	10% 5% 2 4 3 3 4 3 5% 7% 55%	2158
October	1st to 10th	Day	8% 6% 2 4 3 3 4 4 6% 7% 54%	3270
	11th to 20th	Day	5% 5% 1 4 3 4 4 4 6% 10% 54%	3250
	21st to end	Day	6% 9% 4 6% 3 3 3 3 5% 7% 50%	3181
November	1st to 10th	Day	12% 15% 4 8% 6% 5% 4 3 7% 6% 31%	1648
	11th to 20th	Day	6% 11% 4 9% 6% 5% 5% 4 6% 7% 38%	1680
	21st to end	Day	7% 12% 5% 9% 6% 6% 6% 4 6% 7% 32%	1680
December	1st to 10th	Day	5% 16% 7% 11% 5% 5% 5% 3 5% 7% 32%	2399
	11th to 20th	Day	7% 11% 4 12% 5% 6% 6% 5% 6% 7% 31%	2715
	21st to end	Day	3 9% 3 12% 5% 4 5% 4 5% 7% 42%	3575
January	1st to 10th	Night	4 10% 5% 12% 7% 5% 5% 4 6% 8% 34%	8768
	11th to 20th	Night	4 12% 5% 10% 5% 5% 7% 6% 7% 7% 31%	8820
	21st to end	Night	4 9% 5% 10% 5% 5% 4 4 7% 8% 38%	9250
February	1st to 10th	Night	7% 12% 4 10% 6% 6% 6% 5% 6% 7% 31%	2730
	11th to 20th	Night	4 14% 4 9% 7% 6% 6% 5% 7% 7% 31%	2662
	21st to end	Night	4 11% 4 11% 6% 5% 5% 5% 6% 6% 35%	2249
March	1st to 10th	Night	5% 9% 4 11% 6% 5% 5% 4 5% 7% 39%	5285
	11th to 20th	Night	6% 8% 3 7% 5% 5% 5% 4 7% 9% 42%	5110
	21st to end	Night	8% 17% 6% 13% 6% 5% 5% 4 5% 7% 24%	5575
April	1st to 10th	Night	9% 11% 3 7% 6% 5% 5% 5% 6% 6% 36%	2100
	11th to 20th	Night	10% 11% 4 8% 5% 4 4 4 8% 8% 33%	1876
	21st to end	Night	11% 9% 3 7% 5% 5% 5% 4 7% 7% 37%	1879
May	1st to 10th	Night	15% 9% 2 5% 3 3 4 3 5% 7% 44%	4723
	11th to 20th	Night	15% 9% 3 8% 5% 5% 5% 5% 6% 8% 32%	4701
	21st to end	Night	11% 5% 2 5% 4 5% 5% 4 6% 9% 45%	4551
June	1st to 10th	Night	13% 5% 3 6% 4 4 4 4 7% 9% 41%	1470
	11th to 20th	Night	14% 5% 2 6% 4 5% 4 6% 5% 7% 42%	1470
	21st to end	Night	9% 4 1 5% 3 4 4 4 7% 8% 52%	1470
July	1st to 10th	Night	6% 3 2 3 2 3 4 3 6% 8% 60%	3180
	11th to 20th	Night	7% 4 1 4 3 4 5% 4 6% 9% 54%	3180
	21st to end	Night	8% 2 1 2 2 2 3 3 6% 8% 62%	3548
August	1st to 10th	Night	11% 5% 1 5% 4 4 5% 4 6% 7% 49%	3754
	11th to 20th	Night	4 3 1 4 4 4 4 5% 7% 10% 53%	4051
	21st to end	Night	11% 4 1 3 2 3 3 3 4 5% 62%	4509
September	1st to 10th	Night	9% 3 1 5% 3 4 4 3 5% 7% 57%	1994
	11th to 20th	Night	12% 6% 2 4 3 3 4 3 6% 8% 47%	2077
	21st to end	Night	8% 5% 2 4 3 3 4 4 6% 8% 54%	2241
October	1st to 10th	Night	9% 6% 2 5% 3 3 4 4 6% 7% 51%	3920
	11th to 20th	Night	7% 5% 2 5% 3 4 4 3 6% 9% 50%	3898
	21st to end	Night	7% 9% 2 6% 4 4 4 3 5% 6% 50%	4585
November	1st to 10th	Night	12% 13% 4 7% 4 4 4 4 5% 7% 37%	2870
	11th to 20th	Night	7% 11% 4 9% 5% 5% 4 4 5% 7% 39%	2940
	21st to end	Night	5% 13% 5% 9% 5% 5% 5% 4 6% 7% 36%	2940
December	1st to 10th	Night	8% 17% 4 9% 7% 5% 5% 4 5% 6% 31%	4998
	11th to 20th	Night	6% 13% 5% 11% 6% 6% 6% 4 6% 8% 30%	5696
	21st to end	Night	4 8% 3 10% 4 4 4 3 5% 7% 47%	7623

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	52% 8% 17% 17% 6%	4125
	11th to 20th	Day	47% 7% 14% 19% 12% 1	4140
	21st to end	Day	42% 5% 24% 21% 8%	4983
February	1st to 10th	Day	54% 6% 12% 17% 9% 1	1890
	11th to 20th	Day	50% 7% 15% 18% 9% 1	1854
	21st to end	Day	48% 9% 15% 18% 8% 1	1557
March	1st to 10th	Day	39% 6% 16% 26% 12%	4819
	11th to 20th	Day	41% 7% 20% 23% 9%	5110
	21st to end	Day	54% 10% 17% 15% 4	5640
April	1st to 10th	Day	44% 9% 16% 22% 9%	2520
	11th to 20th	Day	50% 8% 13% 21% 7% 1	2693
	21st to end	Day	43% 9% 14% 25% 8% 1	2740
May	1st to 10th	Day	41% 7% 12% 25% 13% 3	8224
	11th to 20th	Day	46% 9% 12% 23% 9%	8195
	21st to end	Day	34% 8% 14% 31% 12% 1	9610
June	1st to 10th	Day	42% 9% 16% 22% 9% 1	3150
	11th to 20th	Day	45% 8% 15% 22% 10% 1	3150
	21st to end	Day	31% 9% 19% 30% 10% 1	3150
July	1st to 10th	Day	26% 7% 20% 21% 20% 5%	6707
	11th to 20th	Day	29% 8% 17% 27% 15% 3	6699
	21st to end	Day	23% 5% 13% 31% 20% 8%	7093
August	1st to 10th	Day	27% 7% 13% 32% 20% 2	4408
	11th to 20th	Day	23% 7% 16% 38% 13% 1	4197
	21st to end	Day	22% 5% 12% 39% 20% 2	4663
September	1st to 10th	Day	33% 6% 11% 26% 17% 7%	2406
	11th to 20th	Day	34% 6% 15% 28% 14% 3	2320
	21st to end	Day	29% 6% 15% 30% 19% 2	2158
October	1st to 10th	Day	29% 5% 13% 34% 16% 3	3270
	11th to 20th	Day	26% 6% 18% 34% 13% 2	3250
	21st to end	Day	34% 5% 12% 38% 11%	3181
November	1st to 10th	Day	51% 8% 13% 18% 8% 1	1648
	11th to 20th	Day	44% 7% 19% 22% 7% 1	1680
	21st to end	Day	49% 7% 19% 16% 8% 1	1680
December	1st to 10th	Day	53% 5% 22% 16% 4 1	2399
	11th to 20th	Day	52% 7% 20% 17% 3 1	2714
	21st to end	Day	40% 5% 11% 25% 12% 6%	3575
January	1st to 10th	Night	48% 7% 16% 20% 9% 1	8769
	11th to 20th	Night	48% 7% 18% 15% 11% 1	8820
	21st to end	Night	43% 6% 21% 23% 7%	9250
February	1st to 10th	Night	50% 6% 15% 17% 10% 1	2730
	11th to 20th	Night	48% 9% 15% 14% 13% 1	2663
	21st to end	Night	46% 7% 15% 23% 9% 1	2249
March	1st to 10th	Night	42% 8% 19% 18% 14%	5285
	11th to 20th	Night	35% 8% 20% 29% 8% 1	5110
	21st to end	Night	57% 9% 14% 15% 5% 1	5575
April	1st to 10th	Night	45% 8% 14% 22% 10% 1	2100
	11th to 20th	Night	46% 8% 13% 22% 10% 2	1876
	21st to end	Night	43% 8% 14% 24% 10% 1	1879
May	1st to 10th	Night	39% 5% 8% 26% 17% 4	4724
	11th to 20th	Night	45% 8% 13% 19% 13%	4702
	21st to end	Night	32% 9% 15% 31% 12% 1	4552
June	1st to 10th	Night	37% 10% 15% 24% 11% 2	1470
	11th to 20th	Night	39% 6% 13% 26% 15% 1	1470
	21st to end	Night	28% 9% 17% 34% 11% 2	1470
July	1st to 10th	Night	22% 6% 18% 28% 23% 4	3145
	11th to 20th	Night	25% 7% 16% 29% 18% 4	3138
	21st to end	Night	20% 5% 13% 32% 23% 8%	3448
August	1st to 10th	Night	26% 6% 12% 32% 21% 3	2725
	11th to 20th	Night	26% 8% 15% 34% 14% 3	2928
	21st to end	Night	27% 5% 11% 33% 21% 3	3245
September	1st to 10th	Night	27% 5% 12% 27% 18% 10%	1994
	11th to 20th	Night	34% 8% 13% 26% 15% 5%	2077
	21st to end	Night	27% 7% 14% 31% 19% 3	2241
October	1st to 10th	Night	32% 6% 11% 34% 17% 1	3920
	11th to 20th	Night	30% 5% 15% 31% 18% 1	3898
	21st to end	Night	34% 6% 11% 37% 11% 1	4585
November	1st to 10th	Night	47% 7% 14% 21% 9% 2	2870
	11th to 20th	Night	45% 7% 19% 20% 10%	2940
	21st to end	Night	47% 7% 20% 19% 7%	2940
December	1st to 10th	Night	54% 6% 20% 13% 5%	4998
	11th to 20th	Night	52% 8% 23% 14% 3 1	5697
	21st to end	Night	37% 4 11% 27% 14% 6%	7623

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	9% 16% 31% 29% 10% 5%	220
	11th to 20th	Day	8% 14% 35% 26% 15% 2	220
	21st to end	Day	9% 15% 37% 31% 9%	275
February	1st to 10th	Day	15% 12% 41% 25% 7%	330
	11th to 20th	Day	10% 10% 35% 29% 15% 1	330
	21st to end	Day	8% 11% 38% 30% 11% 2	273
March	1st to 10th	Day	12% 13% 32% 29% 13% 1	466
	11th to 20th	Day	8% 16% 37% 27% 8% 3	540
	21st to end	Day	13% 14% 34% 26% 12% 2	594
April	1st to 10th	Day	13% 15% 36% 25% 9% 2	540
	11th to 20th	Day	12% 17% 36% 25% 8% 2	532
	21st to end	Day	17% 12% 25% 33% 11% 3	550
May	1st to 10th	Day	14% 7% 24% 32% 18% 5%	753
	11th to 20th	Day	14% 7% 26% 31% 17% 5%	775
	21st to end	Day	17% 8% 23% 26% 21% 6%	844
June	1st to 10th	Day	15% 10% 28% 26% 17% 4	780
	11th to 20th	Day	16% 12% 34% 23% 12% 2	780
	21st to end	Day	11% 7% 26% 30% 21% 5%	780
July	1st to 10th	Day	6% 4 21% 39% 24% 5%	722
	11th to 20th	Day	8% 6% 26% 37% 18% 5%	718
	21st to end	Day	5% 7% 22% 32% 27% 7%	794
August	1st to 10th	Day	7% 6% 21% 36% 23% 7%	650
	11th to 20th	Day	6% 5% 21% 36% 26% 7%	517
	21st to end	Day	8% 5% 24% 33% 24% 6%	583
September	1st to 10th	Day	10% 9% 25% 32% 20% 5%	530
	11th to 20th	Day	15% 5% 25% 31% 18% 5%	530
	21st to end	Day	13% 10% 31% 29% 13% 4	488
October	1st to 10th	Day	17% 8% 26% 25% 18% 6%	330
	11th to 20th	Day	10% 11% 32% 32% 13% 2	330
	21st to end	Day	14% 14% 39% 23% 9% 1	363
November	1st to 10th	Day	21% 12% 34% 24% 9%	330
	11th to 20th	Day	12% 19% 37% 22% 9% 1	330
	21st to end	Day	12% 12% 37% 22% 12% 4	330
December	1st to 10th	Day	12% 12% 38% 28% 9% 2	234
	11th to 20th	Day	10% 25% 32% 26% 6%	220
	21st to end	Day	10% 12% 29% 32% 14% 3	242
January	1st to 10th	Night	10% 16% 38% 28% 8% 1	1050
	11th to 20th	Night	12% 14% 41% 25% 8% 1	1050
	21st to end	Night	11% 15% 37% 28% 8% 1	1081
February	1st to 10th	Night	11% 11% 34% 31% 11% 2	840
	11th to 20th	Night	9% 13% 37% 31% 10% 1	824
	21st to end	Night	9% 8% 33% 34% 13% 2	692
March	1st to 10th	Night	9% 11% 38% 33% 10%	840
	11th to 20th	Night	10% 12% 35% 32% 9% 1	840
	21st to end	Night	12% 12% 34% 29% 11% 1	914
April	1st to 10th	Night	13% 10% 35% 32% 9% 1	630
	11th to 20th	Night	15% 8% 37% 31% 8% 1	623
	21st to end	Night	14% 10% 29% 36% 11%	630
May	1st to 10th	Night	16% 6% 23% 39% 14% 1	630
	11th to 20th	Night	14% 5% 29% 35% 16% 1	621
	21st to end	Night	18% 6% 25% 30% 19% 2	468
June	1st to 10th	Night	14% 10% 29% 29% 17% 2	420
	11th to 20th	Night	16% 9% 30% 35% 9%	420
	21st to end	Night	11% 5% 22% 42% 18% 1	420
July	1st to 10th	Night	7% 4 21% 49% 18% 1	390
	11th to 20th	Night	7% 5% 28% 43% 16% 1	388
	21st to end	Night	5% 3 23% 44% 24% 1	468
August	1st to 10th	Night	9% 2 22% 43% 22% 2	597
	11th to 20th	Night	6% 4 20% 44% 25% 1	594
	21st to end	Night	10% 4 26% 39% 20% 1	660
September	1st to 10th	Night	9% 3 28% 41% 17% 2	600
	11th to 20th	Night	13% 5% 23% 40% 17% 1	677
	21st to end	Night	10% 6% 35% 36% 12% 2	800
October	1st to 10th	Night	15% 7% 29% 35% 14% 1	800
	11th to 20th	Night	12% 10% 35% 33% 10% 2	800
	21st to end	Night	13% 14% 36% 30% 7%	955
November	1st to 10th	Night	19% 12% 38% 27% 5%	1025
	11th to 20th	Night	12% 16% 39% 25% 7% 1	1050
	21st to end	Night	10% 11% 42% 29% 7% 1	1050
December	1st to 10th	Night	12% 10% 41% 25% 9% 1	1050
	11th to 20th	Night	10% 15% 39% 27% 8% 1	1050
	21st to end	Night	12% 11% 39% 29% 9% 1	1155

Page generated at 2026-06-28 00:10:45. Version ac07

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