Rexburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rexburg clear sky chart from 2005-11-06 to 2026-04-17.

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% 9% 3 6% 4 3 4 3 5% 6% 50%	140349
	Night	9% 10% 3 7% 4 4 4 3 5% 6% 45%	139237
Transparency	Day	36% 4 10% 22% 19% 10%	135053
	Night	41% 4 12% 21% 15% 8%	135537
Seeing	Day	12% 9% 23% 29% 20% 6%	17200
	Night	15% 5% 20% 40% 18% 2	26926

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	14% 26% 7% 11% 4 3 3 3 4 4 21%	4466
	11th to 20th	Day	8% 10% 5% 12% 6% 4 3 2 3 4 42%	4894
	21st to end	Day	10% 15% 5% 10% 4 3 3 3 4 5% 38%	5844
February	1st to 10th	Day	16% 16% 5% 11% 5% 5% 4 3 4 4 27%	1890
	11th to 20th	Day	14% 17% 6% 11% 5% 3 4 3 5% 5% 27%	1845
	21st to end	Day	10% 17% 6% 10% 5% 4 4 3 5% 5% 31%	1725
March	1st to 10th	Day	9% 16% 5% 9% 5% 4 4 3 5% 7% 34%	4878
	11th to 20th	Day	9% 14% 4 8% 4 3 4 3 3 5% 43%	5110
	21st to end	Day	9% 14% 4 10% 6% 5% 6% 5% 6% 6% 28%	5607
April	1st to 10th	Day	11% 12% 3 6% 5% 4 5% 5% 6% 7% 37%	2391
	11th to 20th	Day	9% 11% 3 6% 5% 5% 4 3 5% 7% 42%	2646
	21st to end	Day	9% 11% 3 7% 5% 5% 4 4 6% 7% 40%	2600
May	1st to 10th	Day	9% 8% 2 5% 3 3 3 3 5% 7% 52%	5880
	11th to 20th	Day	8% 6% 2 6% 4 5% 5% 4 6% 8% 45%	5874
	21st to end	Day	7% 6% 2 5% 3 3 4 3 5% 6% 56%	6925
June	1st to 10th	Day	9% 4 2 5% 5% 4 5% 4 7% 8% 47%	2935
	11th to 20th	Day	10% 5% 2 5% 4 3 4 3 6% 7% 52%	3000
	21st to end	Day	3 2 1 4 2 3 3 3 4 7% 68%	3000
July	1st to 10th	Day	1 2 1 3 2 3 3 3 4 6% 72%	6779
	11th to 20th	Day	1 2 1 3 2 2 3 3 4 6% 73%	6334
	21st to end	Day	2 2 1 3 3 3 4 3 5% 7% 68%	6401
August	1st to 10th	Day	4 4 2 4 3 3 4 4 6% 7% 61%	5779
	11th to 20th	Day	3 1 1 2 2 3 3 3 5% 7% 70%	5798
	21st to end	Day	5% 3 1 4 3 3 3 3 4 5% 65%	6468
September	1st to 10th	Day	5% 3 1 3 3 3 3 2 4 5% 69%	2335
	11th to 20th	Day	7% 3 2 4 4 4 3 3 4 7% 61%	2200
	21st to end	Day	8% 5% 1 4 2 2 2 2 4 6% 63%	2200
October	1st to 10th	Day	8% 4 2 4 3 2 3 2 3 4 66%	3402
	11th to 20th	Day	6% 5% 2 5% 4 3 3 2 3 5% 62%	3250
	21st to end	Day	9% 10% 3 7% 4 4 4 3 5% 6% 45%	3396
November	1st to 10th	Day	15% 11% 3 6% 4 3 4 3 4 6% 42%	1854
	11th to 20th	Day	13% 11% 3 7% 5% 4 5% 4 5% 6% 38%	1722
	21st to end	Day	11% 15% 5% 7% 4 3 3 3 4 5% 40%	1680
December	1st to 10th	Day	9% 11% 5% 10% 3 2 2 2 3 6% 47%	2700
	11th to 20th	Day	16% 21% 7% 13% 4 4 4 3 3 4 22%	2966
	21st to end	Day	15% 17% 6% 10% 4 4 4 3 5% 6% 26%	3575
January	1st to 10th	Night	14% 20% 6% 15% 5% 4 4 3 4 4 22%	8468
	11th to 20th	Night	11% 15% 4 11% 5% 3 2 2 3 5% 39%	8070
	21st to end	Night	11% 15% 4 8% 3 3 3 2 3 5% 41%	8370
February	1st to 10th	Night	16% 17% 4 10% 5% 3 4 3 5% 5% 28%	2730
	11th to 20th	Night	15% 18% 5% 9% 4 4 3 3 4 4 31%	2662
	21st to end	Night	11% 17% 5% 12% 5% 4 4 4 4 6% 29%	2078
March	1st to 10th	Night	9% 15% 5% 9% 6% 4 4 3 4 5% 37%	5235
	11th to 20th	Night	9% 11% 3 7% 4 3 4 3 5% 7% 44%	5110
	21st to end	Night	9% 12% 3 8% 5% 5% 6% 4 7% 8% 34%	5610
April	1st to 10th	Night	11% 12% 3 7% 4 4 4 4 5% 8% 38%	2226
	11th to 20th	Night	10% 10% 3 7% 5% 4 5% 3 6% 7% 41%	1835
	21st to end	Night	10% 8% 2 6% 4 4 4 4 6% 7% 45%	1800
May	1st to 10th	Night	8% 9% 2 6% 4 3 4 3 4 6% 50%	4100
	11th to 20th	Night	8% 6% 2 6% 5% 5% 5% 4 6% 8% 45%	4038
	21st to end	Night	7% 5% 2 6% 4 4 5% 4 7% 8% 49%	3972
June	1st to 10th	Night	8% 5% 2 5% 5% 4 5% 5% 8% 7% 47%	1460
	11th to 20th	Night	10% 4 1 5% 3 4 4 3 6% 7% 53%	1400
	21st to end	Night	3 2 1 3 2 3 4 3 5% 7% 68%	1400
July	1st to 10th	Night	2 1 1 3 2 3 3 3 6% 6% 69%	3180
	11th to 20th	Night	1 1 1 2 3 3 4 4 5% 8% 69%	3622
	21st to end	Night	2 2 1 3 3 3 4 4 6% 8% 65%	4472
August	1st to 10th	Night	4 2 1 4 3 3 4 3 6% 8% 61%	4033
	11th to 20th	Night	1 1 1 3 3 3 4 3 4 7% 69%	4051
	21st to end	Night	8% 5% 1 5% 3 2 2 3 4 6% 62%	4509
September	1st to 10th	Night	5% 3 1 3 2 3 2 3 5% 5% 68%	2061
	11th to 20th	Night	6% 4 1 4 4 3 4 3 5% 7% 60%	2200
	21st to end	Night	8% 4 1 3 2 2 3 2 4 6% 64%	2200
October	1st to 10th	Night	6% 4 1 3 3 2 2 2 3 4 70%	3792
	11th to 20th	Night	12% 7% 2 5% 3 3 3 3 4 5% 55%	3898
	21st to end	Night	9% 9% 3 6% 4 4 4 4 6% 7% 45%	4402
November	1st to 10th	Night	14% 9% 3 5% 4 4 4 4 5% 6% 44%	2665
	11th to 20th	Night	14% 12% 2 7% 4 4 4 3 5% 6% 38%	2876
	21st to end	Night	11% 12% 5% 7% 5% 4 4 3 4 5% 40%	2940
December	1st to 10th	Night	10% 11% 4 8% 5% 3 3 2 3 5% 46%	4710
	11th to 20th	Night	14% 20% 5% 9% 4 4 4 3 4 6% 26%	5439
	21st to end	Night	16% 18% 5% 9% 4 4 4 3 4 5% 28%	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	68% 4 14% 11% 3	4467
	11th to 20th	Day	47% 4 22% 16% 9% 2	4894
	21st to end	Day	50% 4 13% 20% 11% 1	5844
February	1st to 10th	Day	61% 6% 12% 17% 4 1	1890
	11th to 20th	Day	59% 5% 14% 16% 5% 1	1854
	21st to end	Day	52% 8% 13% 19% 7% 1	1725
March	1st to 10th	Day	48% 4 15% 21% 9% 2	4878
	11th to 20th	Day	44% 3 10% 30% 11% 1	5110
	21st to end	Day	55% 5% 14% 21% 5%	5607
April	1st to 10th	Day	45% 6% 14% 22% 12% 1	2391
	11th to 20th	Day	40% 4 11% 27% 14% 2	2649
	21st to end	Day	42% 5% 11% 28% 14% 1	2600
May	1st to 10th	Day	32% 4 8% 29% 21% 5%	5880
	11th to 20th	Day	35% 5% 7% 27% 19% 6%	5877
	21st to end	Day	29% 3 7% 36% 22% 2	6926
June	1st to 10th	Day	33% 5% 13% 30% 18% 1	2935
	11th to 20th	Day	31% 4 9% 22% 23% 11%	3000
	21st to end	Day	17% 3 5% 24% 33% 19%	3000
July	1st to 10th	Day	14% 3 2 12% 32% 37%	6706
	11th to 20th	Day	13% 2 2 13% 30% 40%	6257
	21st to end	Day	16% 3 3 13% 37% 29%	6217
August	1st to 10th	Day	24% 3 4 17% 30% 23%	4208
	11th to 20th	Day	15% 3 4 21% 38% 20%	4197
	21st to end	Day	18% 3 4 21% 28% 27%	4663
September	1st to 10th	Day	18% 3 7% 18% 33% 22%	2335
	11th to 20th	Day	25% 3 8% 25% 27% 12%	2200
	21st to end	Day	23% 3 8% 28% 28% 10%	2200
October	1st to 10th	Day	24% 3 7% 21% 38% 7%	3402
	11th to 20th	Day	27% 2 10% 37% 18% 5%	3250
	21st to end	Day	40% 3 14% 27% 15% 1	3396
November	1st to 10th	Day	45% 4 18% 23% 10% 1	1854
	11th to 20th	Day	46% 6% 18% 22% 6% 2	1722
	21st to end	Day	47% 5% 19% 21% 8% 1	1680
December	1st to 10th	Day	41% 5% 24% 25% 3 1	2700
	11th to 20th	Day	67% 5% 14% 13% 2	2964
	21st to end	Day	60% 4 14% 15% 5%	3575
January	1st to 10th	Night	67% 4 9% 17% 4	8469
	11th to 20th	Night	51% 5% 22% 15% 6% 1	8070
	21st to end	Night	48% 4 15% 21% 8% 4	8370
February	1st to 10th	Night	58% 5% 15% 16% 5% 1	2730
	11th to 20th	Night	57% 4 14% 18% 6% 1	2663
	21st to end	Night	55% 5% 14% 17% 7% 1	2078
March	1st to 10th	Night	49% 4 12% 22% 9% 4	5235
	11th to 20th	Night	40% 4 13% 29% 12% 1	5110
	21st to end	Night	46% 6% 17% 25% 6%	5610
April	1st to 10th	Night	44% 6% 13% 23% 12% 2	2226
	11th to 20th	Night	41% 6% 12% 24% 15% 2	1835
	21st to end	Night	38% 5% 12% 28% 17%	1800
May	1st to 10th	Night	34% 6% 7% 27% 24% 2	4097
	11th to 20th	Night	34% 6% 9% 28% 18% 5%	4039
	21st to end	Night	31% 5% 8% 27% 27% 3	3972
June	1st to 10th	Night	31% 7% 13% 25% 22% 2	1460
	11th to 20th	Night	30% 5% 7% 23% 24% 12%	1400
	21st to end	Night	16% 4 7% 20% 30% 24%	1400
July	1st to 10th	Night	16% 3 3 12% 25% 41%	3145
	11th to 20th	Night	13% 3 2 11% 31% 40%	3576
	21st to end	Night	17% 3 3 12% 31% 33%	4344
August	1st to 10th	Night	21% 3 4 13% 32% 27%	2928
	11th to 20th	Night	19% 3 3 24% 29% 22%	2928
	21st to end	Night	18% 2 5% 19% 28% 29%	3245
September	1st to 10th	Night	20% 3 5% 14% 33% 25%	2061
	11th to 20th	Night	25% 4 8% 24% 24% 16%	2200
	21st to end	Night	23% 3 7% 23% 34% 11%	2200
October	1st to 10th	Night	20% 2 7% 21% 37% 13%	3792
	11th to 20th	Night	33% 3 7% 34% 17% 6%	3898
	21st to end	Night	38% 4 13% 27% 17% 1	4402
November	1st to 10th	Night	41% 5% 16% 26% 12% 1	2665
	11th to 20th	Night	46% 5% 17% 24% 6% 2	2876
	21st to end	Night	46% 4 19% 20% 9% 1	2940
December	1st to 10th	Night	44% 4 24% 23% 4 1	4710
	11th to 20th	Night	60% 4 20% 13% 2	5440
	21st to end	Night	60% 4 14% 15% 7%	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	26% 9% 18% 20% 21% 5%	220
	11th to 20th	Day	19% 4 16% 35% 20% 6%	248
	21st to end	Day	22% 5% 17% 33% 21% 3	363
February	1st to 10th	Day	25% 10% 27% 24% 12% 3	330
	11th to 20th	Day	21% 7% 29% 28% 13% 2	330
	21st to end	Day	18% 14% 26% 30% 10% 2	441
March	1st to 10th	Day	17% 14% 26% 31% 10% 2	540
	11th to 20th	Day	14% 13% 28% 27% 16% 1	540
	21st to end	Day	15% 19% 30% 26% 9% 1	594
April	1st to 10th	Day	17% 16% 25% 27% 13% 2	540
	11th to 20th	Day	15% 20% 29% 23% 11% 1	517
	21st to end	Day	15% 14% 26% 27% 14% 4	500
May	1st to 10th	Day	14% 12% 24% 27% 18% 5%	503
	11th to 20th	Day	11% 13% 27% 27% 16% 6%	535
	21st to end	Day	15% 7% 20% 26% 23% 8%	789
June	1st to 10th	Day	8% 9% 23% 29% 24% 7%	730
	11th to 20th	Day	12% 13% 25% 29% 18% 3	730
	21st to end	Day	4 7% 22% 36% 25% 5%	730
July	1st to 10th	Day	3 4 24% 37% 25% 7%	721
	11th to 20th	Day	2 6% 24% 39% 25% 3	545
	21st to end	Day	3 5% 22% 34% 26% 10%	575
August	1st to 10th	Day	6% 5% 23% 30% 30% 6%	527
	11th to 20th	Day	4 4 20% 29% 31% 11%	517
	21st to end	Day	6% 7% 21% 30% 23% 12%	583
September	1st to 10th	Day	4 5% 21% 29% 29% 12%	530
	11th to 20th	Day	8% 8% 23% 29% 25% 8%	530
	21st to end	Day	9% 8% 19% 27% 26% 10%	530
October	1st to 10th	Day	10% 5% 19% 29% 27% 9%	410
	11th to 20th	Day	12% 11% 22% 22% 21% 14%	330
	21st to end	Day	16% 11% 20% 29% 20% 4	363
November	1st to 10th	Day	22% 8% 22% 27% 14% 8%	330
	11th to 20th	Day	14% 8% 26% 33% 15% 3	330
	21st to end	Day	18% 7% 21% 33% 19% 2	330
December	1st to 10th	Day	22% 7% 20% 28% 16% 7%	330
	11th to 20th	Day	33% 5% 19% 26% 16% 1	297
	21st to end	Day	26% 9% 15% 25% 19% 6%	242
January	1st to 10th	Night	23% 5% 16% 38% 17% 1	945
	11th to 20th	Night	23% 5% 18% 33% 18% 3	840
	21st to end	Night	21% 3 18% 42% 14% 2	924
February	1st to 10th	Night	25% 5% 22% 35% 12% 1	840
	11th to 20th	Night	22% 5% 23% 37% 11% 2	824
	21st to end	Night	16% 8% 23% 38% 12% 2	692
March	1st to 10th	Night	17% 7% 22% 41% 12% 1	840
	11th to 20th	Night	16% 6% 25% 37% 15% 1	840
	21st to end	Night	16% 8% 26% 37% 13% 1	924
April	1st to 10th	Night	15% 7% 24% 39% 14% 1	777
	11th to 20th	Night	16% 8% 29% 36% 10% 1	611
	21st to end	Night	13% 6% 26% 38% 16% 1	600
May	1st to 10th	Night	9% 9% 26% 37% 18% 1	600
	11th to 20th	Night	9% 8% 24% 36% 22% 1	591
	21st to end	Night	13% 5% 22% 38% 19% 2	650
June	1st to 10th	Night	9% 7% 16% 41% 25% 2	460
	11th to 20th	Night	12% 4 27% 41% 16% 1	400
	21st to end	Night	4 2 17% 52% 25% 2	400
July	1st to 10th	Night	3 1 17% 49% 29% 2	390
	11th to 20th	Night	2 14% 63% 21%	398
	21st to end	Night	3 1 17% 48% 30% 2	657
August	1st to 10th	Night	5% 4 17% 47% 26% 1	597
	11th to 20th	Night	2 2 15% 50% 28% 2	594
	21st to end	Night	6% 2 19% 44% 27% 2	660
September	1st to 10th	Night	5% 2 16% 46% 27% 4	681
	11th to 20th	Night	7% 3 15% 40% 30% 5%	800
	21st to end	Night	10% 3 14% 40% 28% 5%	800
October	1st to 10th	Night	11% 4 16% 45% 23% 1	800
	11th to 20th	Night	14% 5% 19% 38% 22% 3	800
	21st to end	Night	13% 6% 19% 43% 16% 3	880
November	1st to 10th	Night	17% 5% 20% 39% 18% 1	820
	11th to 20th	Night	18% 6% 23% 40% 13% 1	986
	21st to end	Night	16% 5% 21% 38% 18% 2	1050
December	1st to 10th	Night	21% 6% 19% 39% 13% 2	1050
	11th to 20th	Night	24% 6% 18% 39% 12% 1	1050
	21st to end	Night	27% 7% 20% 33% 12% 1	1155

Page generated at 2026-04-14 00:44:26. Version ac07

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