Beaverlodge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beaverlodge 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	9% 10% 4 9% 6% 5% 6% 4 7% 8% 33%	142059
	Night	8% 11% 4 10% 6% 6% 5% 4 6% 8% 32%	138986
Transparency	Day	47% 6% 15% 22% 10% 1	141737
	Night	49% 6% 14% 21% 9% 1	138891
Seeing	Day	15% 10% 24% 28% 18% 6%	18781
	Night	14% 8% 28% 32% 15% 2	26738

By Month

Percentage Cloud Cover NW (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	7% 17% 6% 11% 7% 5% 5% 5% 7% 9% 21%	3527
	11th to 20th	Day	5% 11% 3 9% 6% 7% 7% 5% 9% 8% 30%	3684
	21st to end	Day	7% 11% 4 9% 5% 5% 6% 5% 7% 9% 31%	4708
February	1st to 10th	Day	7% 12% 6% 11% 7% 7% 5% 5% 6% 9% 24%	1680
	11th to 20th	Day	4 15% 7% 13% 6% 6% 6% 4 6% 7% 26%	1727
	21st to end	Day	5% 14% 7% 12% 8% 7% 6% 5% 6% 6% 24%	1620
March	1st to 10th	Day	3 9% 4 14% 10% 9% 6% 4 6% 7% 26%	4618
	11th to 20th	Day	7% 15% 6% 11% 5% 5% 5% 4 6% 9% 27%	4825
	21st to end	Day	6% 13% 5% 13% 6% 5% 5% 4 6% 7% 30%	6072
April	1st to 10th	Day	4 11% 5% 11% 8% 6% 7% 5% 6% 8% 28%	2520
	11th to 20th	Day	7% 13% 5% 11% 6% 4 5% 5% 6% 7% 31%	2701
	21st to end	Day	10% 12% 4 10% 5% 5% 5% 4 6% 8% 31%	2940
May	1st to 10th	Day	6% 7% 3 8% 5% 6% 6% 5% 8% 9% 35%	8195
	11th to 20th	Day	7% 9% 4 10% 7% 8% 7% 6% 7% 9% 26%	8829
	21st to end	Day	12% 8% 3 8% 6% 6% 6% 5% 7% 8% 29%	10305
June	1st to 10th	Day	14% 9% 4 8% 5% 6% 5% 4 6% 7% 33%	3360
	11th to 20th	Day	18% 10% 3 8% 6% 6% 5% 4 6% 6% 27%	3360
	21st to end	Day	12% 7% 3 9% 6% 5% 6% 4 7% 8% 34%	3360
July	1st to 10th	Day	11% 6% 2 7% 4 4 5% 4 6% 8% 42%	7241
	11th to 20th	Day	9% 6% 2 7% 5% 5% 5% 4 6% 8% 44%	7240
	21st to end	Day	12% 5% 2 6% 4 4 5% 4 7% 9% 43%	7570
August	1st to 10th	Day	10% 6% 2 6% 5% 4 4 3 5% 7% 48%	4541
	11th to 20th	Day	12% 6% 2 7% 4 5% 5% 4 7% 9% 38%	4470
	21st to end	Day	14% 7% 3 6% 5% 4 5% 4 6% 8% 40%	4744
September	1st to 10th	Day	12% 6% 2 6% 5% 4 4 4 5% 8% 43%	2400
	11th to 20th	Day	13% 8% 2 6% 5% 5% 4 3 5% 8% 40%	2386
	21st to end	Day	13% 7% 2 7% 5% 5% 5% 4 6% 9% 37%	2160
October	1st to 10th	Day	12% 10% 3 9% 5% 6% 5% 4 5% 8% 32%	3280
	11th to 20th	Day	11% 11% 4 10% 5% 5% 6% 5% 7% 7% 30%	3014
	21st to end	Day	10% 13% 4 9% 4 4 5% 4 7% 8% 32%	3104
November	1st to 10th	Day	13% 17% 4 9% 5% 5% 4 4 6% 7% 26%	1600
	11th to 20th	Day	11% 15% 5% 11% 6% 5% 4 4 5% 6% 28%	1470
	21st to end	Day	9% 14% 4 12% 8% 5% 5% 4 5% 7% 27%	1408
December	1st to 10th	Day	13% 19% 5% 11% 8% 5% 6% 3 5% 5% 21%	2020
	11th to 20th	Day	10% 17% 5% 9% 8% 7% 5% 4 6% 7% 20%	2322
	21st to end	Day	4 9% 4 10% 5% 4 5% 4 8% 9% 38%	3058
January	1st to 10th	Night	6% 17% 7% 14% 7% 4 4 4 6% 7% 22%	9366
	11th to 20th	Night	4 10% 4 10% 7% 6% 6% 6% 8% 9% 29%	9256
	21st to end	Night	7% 14% 4 9% 5% 6% 6% 4 6% 9% 29%	9471
February	1st to 10th	Night	8% 15% 6% 11% 7% 5% 5% 4 6% 7% 25%	2940
	11th to 20th	Night	6% 13% 6% 12% 6% 6% 6% 5% 6% 8% 27%	2778
	21st to end	Night	4 13% 5% 12% 7% 6% 6% 4 6% 8% 27%	2185
March	1st to 10th	Night	2 9% 4 14% 9% 7% 7% 5% 7% 7% 29%	5496
	11th to 20th	Night	6% 14% 5% 11% 6% 5% 6% 5% 7% 9% 26%	5390
	21st to end	Night	7% 11% 4 10% 5% 4 4 3 5% 9% 38%	5145
April	1st to 10th	Night	4 11% 5% 11% 7% 6% 7% 5% 7% 8% 29%	2100
	11th to 20th	Night	9% 10% 4 9% 6% 5% 5% 5% 6% 7% 33%	1865
	21st to end	Night	10% 10% 4 8% 5% 6% 6% 5% 7% 5% 34%	1680
May	1st to 10th	Night	7% 10% 3 10% 5% 5% 5% 5% 6% 7% 37%	4724
	11th to 20th	Night	7% 9% 4 9% 7% 7% 6% 5% 7% 8% 30%	4029
	21st to end	Night	8% 7% 3 8% 6% 6% 7% 6% 8% 9% 32%	3866
June	1st to 10th	Night	11% 8% 5% 9% 7% 5% 5% 3 5% 7% 34%	1260
	11th to 20th	Night	18% 9% 3 8% 6% 5% 6% 5% 8% 8% 26%	1260
	21st to end	Night	13% 6% 3 7% 5% 5% 5% 4 7% 9% 35%	1260
July	1st to 10th	Night	11% 6% 2 6% 4 6% 5% 4 7% 7% 41%	2720
	11th to 20th	Night	10% 6% 3 7% 5% 6% 5% 4 7% 8% 42%	2720
	21st to end	Night	9% 5% 2 7% 5% 5% 6% 5% 7% 9% 41%	3270
August	1st to 10th	Night	8% 4 2 6% 4 4 4 4 6% 9% 50%	2609
	11th to 20th	Night	11% 5% 2 5% 5% 5% 5% 5% 6% 8% 43%	2577
	21st to end	Night	10% 5% 2 8% 5% 7% 6% 4 6% 8% 38%	3159
September	1st to 10th	Night	12% 6% 3 8% 5% 5% 5% 3 6% 6% 41%	2000
	11th to 20th	Night	11% 8% 2 6% 4 4 5% 4 5% 8% 42%	2014
	21st to end	Night	13% 8% 3 8% 4 5% 5% 4 6% 7% 37%	2238
October	1st to 10th	Night	11% 10% 3 9% 6% 5% 5% 4 6% 8% 32%	3920
	11th to 20th	Night	7% 7% 3 8% 5% 5% 6% 4 6% 9% 39%	4135
	21st to end	Night	9% 12% 4 10% 6% 6% 6% 4 6% 7% 30%	4689
November	1st to 10th	Night	13% 15% 4 9% 6% 5% 4 3 6% 7% 26%	2896
	11th to 20th	Night	9% 15% 5% 11% 6% 4 4 4 6% 7% 28%	3150
	21st to end	Night	9% 18% 5% 10% 7% 5% 5% 3 6% 6% 28%	3208
December	1st to 10th	Night	10% 14% 5% 11% 7% 6% 5% 4 5% 6% 27%	5380
	11th to 20th	Night	10% 18% 5% 13% 7% 6% 5% 3 4 6% 22%	6090
	21st to end	Night	4 12% 4 11% 6% 6% 6% 4 6% 7% 33%	8140

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	57% 4 11% 17% 10% 1	3527
	11th to 20th	Day	48% 6% 16% 18% 11% 2	3702
	21st to end	Day	48% 8% 22% 16% 7%	4709
February	1st to 10th	Day	55% 8% 12% 11% 13% 1	1680
	11th to 20th	Day	56% 7% 12% 16% 9% 1	1735
	21st to end	Day	58% 5% 12% 17% 7% 1	1620
March	1st to 10th	Day	55% 6% 8% 21% 11%	4618
	11th to 20th	Day	52% 6% 11% 20% 10%	4825
	21st to end	Day	51% 6% 11% 20% 12%	6072
April	1st to 10th	Day	50% 8% 14% 19% 8% 1	2520
	11th to 20th	Day	51% 6% 13% 18% 11% 1	2701
	21st to end	Day	49% 8% 11% 23% 8% 1	2940
May	1st to 10th	Day	41% 5% 14% 25% 12% 2	8195
	11th to 20th	Day	51% 6% 13% 21% 9% 1	8833
	21st to end	Day	49% 7% 13% 20% 11% 1	10306
June	1st to 10th	Day	49% 6% 12% 20% 10% 1	3360
	11th to 20th	Day	56% 7% 10% 19% 8%	3360
	21st to end	Day	45% 9% 15% 22% 9% 1	3360
July	1st to 10th	Day	38% 6% 15% 21% 19% 2	7162
	11th to 20th	Day	38% 6% 14% 29% 12% 1	7153
	21st to end	Day	36% 7% 21% 27% 8%	7356
August	1st to 10th	Day	36% 7% 15% 33% 9%	4524
	11th to 20th	Day	40% 7% 17% 24% 12%	4512
	21st to end	Day	42% 7% 21% 24% 5%	4743
September	1st to 10th	Day	40% 8% 18% 27% 6% 1	2400
	11th to 20th	Day	42% 7% 17% 26% 8%	2386
	21st to end	Day	43% 9% 15% 23% 9% 1	2160
October	1st to 10th	Day	50% 5% 18% 20% 6%	3280
	11th to 20th	Day	51% 6% 14% 24% 5%	3014
	21st to end	Day	48% 6% 23% 19% 4	3104
November	1st to 10th	Day	55% 7% 12% 19% 6% 1	1600
	11th to 20th	Day	56% 6% 14% 15% 8%	1470
	21st to end	Day	56% 7% 12% 17% 7% 2	1408
December	1st to 10th	Day	66% 6% 13% 10% 6% 1	2020
	11th to 20th	Day	61% 7% 13% 13% 5%	2324
	21st to end	Day	41% 7% 13% 28% 10% 1	3058
January	1st to 10th	Night	60% 4 9% 15% 11% 1	9367
	11th to 20th	Night	49% 5% 15% 18% 12% 1	9300
	21st to end	Night	49% 7% 19% 16% 8%	9471
February	1st to 10th	Night	57% 5% 13% 13% 11%	2940
	11th to 20th	Night	54% 8% 11% 19% 8% 1	2780
	21st to end	Night	54% 7% 12% 20% 7% 1	2185
March	1st to 10th	Night	51% 6% 12% 17% 13%	5496
	11th to 20th	Night	52% 6% 13% 19% 10%	5391
	21st to end	Night	42% 6% 11% 26% 15%	5145
April	1st to 10th	Night	48% 7% 14% 20% 10% 1	2100
	11th to 20th	Night	47% 7% 13% 20% 11% 1	1865
	21st to end	Night	47% 8% 10% 24% 10% 1	1680
May	1st to 10th	Night	44% 5% 11% 29% 10% 1	4721
	11th to 20th	Night	47% 8% 11% 25% 8%	4029
	21st to end	Night	42% 8% 18% 20% 9% 3	3870
June	1st to 10th	Night	49% 6% 10% 23% 11% 1	1260
	11th to 20th	Night	52% 8% 13% 21% 6%	1260
	21st to end	Night	44% 7% 18% 21% 10%	1260
July	1st to 10th	Night	40% 6% 15% 24% 14% 1	2690
	11th to 20th	Night	39% 7% 12% 28% 14%	2684
	21st to end	Night	36% 8% 20% 29% 6%	3179
August	1st to 10th	Night	31% 8% 19% 36% 6%	2601
	11th to 20th	Night	37% 8% 14% 29% 10% 1	2601
	21st to end	Night	43% 7% 23% 21% 5% 1	3159
September	1st to 10th	Night	42% 8% 17% 25% 7% 1	2000
	11th to 20th	Night	39% 7% 18% 28% 8%	2014
	21st to end	Night	45% 9% 13% 21% 12% 1	2238
October	1st to 10th	Night	50% 6% 16% 20% 8% 1	3920
	11th to 20th	Night	41% 6% 15% 31% 7%	4135
	21st to end	Night	51% 7% 17% 18% 6%	4689
November	1st to 10th	Night	56% 7% 12% 18% 6% 1	2896
	11th to 20th	Night	54% 7% 12% 17% 9%	3150
	21st to end	Night	56% 7% 12% 17% 7% 1	3208
December	1st to 10th	Night	57% 6% 15% 15% 6%	5380
	11th to 20th	Night	64% 5% 14% 12% 5%	6087
	21st to end	Night	49% 6% 13% 24% 6% 1	8140

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% 8% 19% 39% 16% 5%	220
	11th to 20th	Day	14% 11% 26% 30% 16% 3	220
	21st to end	Day	11% 11% 28% 33% 15% 2	242
February	1st to 10th	Day	9% 14% 20% 34% 18% 5%	220
	11th to 20th	Day	10% 13% 21% 31% 19% 5%	307
	21st to end	Day	11% 12% 25% 32% 18% 2	388
March	1st to 10th	Day	9% 10% 26% 29% 20% 5%	540
	11th to 20th	Day	12% 8% 26% 31% 16% 6%	540
	21st to end	Day	14% 10% 25% 25% 22% 5%	594
April	1st to 10th	Day	7% 14% 30% 31% 12% 5%	540
	11th to 20th	Day	13% 12% 26% 31% 12% 6%	532
	21st to end	Day	16% 13% 26% 21% 17% 5%	540
May	1st to 10th	Day	15% 12% 29% 29% 11% 4	543
	11th to 20th	Day	14% 8% 21% 31% 21% 6%	795
	21st to end	Day	16% 8% 25% 26% 20% 6%	1072
June	1st to 10th	Day	16% 13% 26% 28% 14% 3	990
	11th to 20th	Day	23% 8% 22% 23% 19% 5%	990
	21st to end	Day	16% 7% 20% 25% 22% 11%	990
July	1st to 10th	Day	16% 6% 21% 28% 23% 6%	917
	11th to 20th	Day	14% 6% 24% 28% 21% 8%	912
	21st to end	Day	13% 9% 21% 31% 18% 9%	884
August	1st to 10th	Day	14% 7% 18% 28% 20% 13%	527
	11th to 20th	Day	11% 11% 29% 24% 18% 8%	517
	21st to end	Day	16% 8% 26% 22% 17% 11%	583
September	1st to 10th	Day	16% 9% 22% 27% 18% 8%	530
	11th to 20th	Day	15% 8% 25% 24% 21% 6%	530
	21st to end	Day	18% 14% 32% 21% 11% 3	530
October	1st to 10th	Day	17% 13% 23% 27% 15% 5%	530
	11th to 20th	Day	20% 9% 25% 27% 14% 4	386
	21st to end	Day	18% 11% 29% 24% 13% 5%	330
November	1st to 10th	Day	18% 12% 24% 29% 15% 2	220
	11th to 20th	Day	22% 8% 25% 28% 15% 1	220
	21st to end	Day	17% 10% 25% 32% 12% 4	220
December	1st to 10th	Day	12% 10% 31% 32% 10% 4	220
	11th to 20th	Day	17% 12% 23% 29% 16% 3	220
	21st to end	Day	14% 7% 22% 31% 21% 4	242
January	1st to 10th	Night	14% 9% 27% 32% 15% 3	1160
	11th to 20th	Night	13% 13% 29% 31% 13% 2	1118
	21st to end	Night	18% 12% 30% 29% 10% 1	1012
February	1st to 10th	Night	17% 11% 23% 28% 16% 5%	840
	11th to 20th	Night	12% 8% 28% 34% 16% 1	824
	21st to end	Night	9% 10% 26% 35% 16% 4	692
March	1st to 10th	Night	9% 9% 29% 31% 19% 3	840
	11th to 20th	Night	14% 6% 28% 36% 14% 2	840
	21st to end	Night	13% 6% 24% 34% 20% 3	924
April	1st to 10th	Night	10% 8% 29% 35% 15% 3	840
	11th to 20th	Night	12% 9% 28% 34% 15% 2	617
	21st to end	Night	13% 10% 30% 30% 16% 1	420
May	1st to 10th	Night	14% 9% 29% 35% 12% 2	420
	11th to 20th	Night	14% 7% 27% 34% 16% 2	414
	21st to end	Night	13% 7% 26% 32% 20% 2	455
June	1st to 10th	Night	13% 9% 27% 33% 18%	420
	11th to 20th	Night	21% 5% 20% 33% 18% 3	420
	21st to end	Night	15% 3 26% 32% 22% 3	420
July	1st to 10th	Night	14% 4 20% 40% 21% 2	390
	11th to 20th	Night	15% 5% 25% 30% 23% 3	388
	21st to end	Night	12% 2 21% 37% 24% 4	438
August	1st to 10th	Night	11% 4 20% 33% 29% 5%	398
	11th to 20th	Night	7% 5% 29% 34% 22% 3	396
	21st to end	Night	15% 6% 27% 30% 21% 2	600
September	1st to 10th	Night	15% 5% 23% 36% 19% 2	800
	11th to 20th	Night	16% 5% 23% 33% 21% 2	800
	21st to end	Night	17% 10% 30% 28% 13% 2	800
October	1st to 10th	Night	18% 7% 30% 32% 12% 1	800
	11th to 20th	Night	15% 8% 30% 36% 11% 2	800
	21st to end	Night	18% 12% 30% 29% 9% 1	880
November	1st to 10th	Night	19% 8% 29% 30% 13% 2	846
	11th to 20th	Night	15% 12% 35% 29% 9% 1	1050
	21st to end	Night	15% 11% 30% 30% 11% 2	1080
December	1st to 10th	Night	13% 10% 32% 32% 10% 2	1160
	11th to 20th	Night	15% 10% 27% 31% 14% 3	1160
	21st to end	Night	14% 8% 26% 35% 15% 2	1276

Page generated at 2026-06-28 00:10:46. Version ac07

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