Dawson Creek
Clear Sky Chart
History

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

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% 9% 3 9% 6% 6% 6% 4 7% 8% 34%	135727
	Night	7% 11% 4 10% 6% 6% 6% 4 6% 8% 33%	136116
Transparency	Day	47% 5% 15% 22% 10% 1	135405
	Night	48% 5% 14% 21% 10% 1	136018
Seeing	Day	15% 14% 28% 25% 15% 4	18710
	Night	14% 12% 27% 30% 15% 2	26697

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	5% 16% 7% 13% 6% 7% 6% 3 5% 9% 23%	3527
	11th to 20th	Day	4 11% 4 9% 6% 7% 7% 5% 7% 8% 31%	3702
	21st to end	Day	5% 9% 4 10% 6% 5% 6% 5% 7% 10% 33%	4529
February	1st to 10th	Day	6% 13% 4 12% 6% 7% 6% 5% 7% 8% 27%	1676
	11th to 20th	Day	4 14% 5% 12% 7% 6% 6% 4 6% 8% 28%	1743
	21st to end	Day	5% 13% 6% 14% 7% 6% 6% 4 6% 7% 26%	1584
March	1st to 10th	Day	3 8% 4 13% 10% 8% 7% 5% 7% 8% 27%	4618
	11th to 20th	Day	6% 15% 5% 12% 7% 5% 5% 4 7% 9% 25%	4882
	21st to end	Day	4 13% 5% 12% 6% 5% 5% 4 6% 7% 33%	6011
April	1st to 10th	Day	4 12% 4 8% 7% 6% 7% 6% 6% 8% 32%	2520
	11th to 20th	Day	7% 12% 5% 9% 6% 5% 6% 4 6% 8% 31%	2731
	21st to end	Day	9% 9% 4 9% 6% 6% 6% 5% 7% 8% 31%	2940
May	1st to 10th	Day	7% 7% 3 7% 5% 6% 6% 6% 8% 9% 36%	6460
	11th to 20th	Day	6% 8% 4 10% 7% 7% 7% 5% 7% 9% 28%	7099
	21st to end	Day	10% 9% 3 10% 6% 6% 6% 6% 8% 9% 27%	8083
June	1st to 10th	Day	12% 8% 3 7% 6% 5% 5% 5% 7% 7% 34%	3201
	11th to 20th	Day	17% 10% 4 9% 6% 6% 6% 4 6% 8% 25%	3200
	21st to end	Day	10% 7% 2 8% 6% 5% 6% 5% 8% 9% 34%	3200
July	1st to 10th	Day	11% 6% 2 7% 4 5% 5% 4 7% 8% 42%	7240
	11th to 20th	Day	8% 6% 2 7% 5% 5% 5% 4 6% 8% 44%	7240
	21st to end	Day	9% 6% 2 6% 4 5% 5% 4 7% 9% 43%	7590
August	1st to 10th	Day	9% 5% 2 5% 4 5% 5% 3 5% 7% 48%	4612
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 4 7% 9% 38%	4470
	21st to end	Day	12% 6% 2 6% 5% 4 4 4 7% 9% 41%	4770
September	1st to 10th	Day	12% 5% 3 7% 5% 4 4 4 6% 8% 41%	2400
	11th to 20th	Day	11% 7% 2 7% 5% 5% 4 4 6% 9% 41%	2400
	21st to end	Day	10% 9% 2 7% 5% 6% 6% 5% 6% 9% 36%	2137
October	1st to 10th	Day	13% 11% 3 8% 5% 5% 5% 4 7% 7% 32%	3280
	11th to 20th	Day	10% 10% 3 8% 5% 5% 6% 5% 6% 8% 33%	3046
	21st to end	Day	9% 12% 4 9% 4 4 5% 5% 6% 8% 35%	3021
November	1st to 10th	Day	14% 12% 5% 11% 5% 4 4 3 6% 7% 30%	1611
	11th to 20th	Day	9% 15% 6% 9% 7% 4 5% 4 6% 6% 29%	1470
	21st to end	Day	8% 14% 4 11% 7% 5% 5% 3 7% 7% 29%	1334
December	1st to 10th	Day	10% 21% 5% 10% 6% 5% 6% 4 6% 6% 21%	2020
	11th to 20th	Day	8% 14% 5% 12% 8% 9% 7% 5% 6% 8% 18%	2322
	21st to end	Day	3 8% 3 9% 6% 5% 5% 5% 8% 8% 40%	3058
January	1st to 10th	Night	4 15% 7% 15% 8% 6% 6% 4 5% 6% 24%	9366
	11th to 20th	Night	3 9% 4 10% 7% 6% 6% 6% 9% 8% 31%	9242
	21st to end	Night	7% 12% 4 8% 5% 6% 6% 5% 6% 9% 32%	9651
February	1st to 10th	Night	6% 15% 5% 10% 7% 8% 5% 4 6% 8% 26%	2943
	11th to 20th	Night	5% 13% 6% 11% 8% 5% 5% 5% 7% 8% 27%	2763
	21st to end	Night	3 13% 5% 12% 7% 7% 8% 4 6% 7% 28%	2222
March	1st to 10th	Night	2 9% 3 13% 8% 7% 7% 6% 7% 8% 31%	5496
	11th to 20th	Night	5% 13% 6% 13% 7% 6% 5% 4 7% 9% 26%	5334
	21st to end	Night	6% 10% 3 8% 4 5% 4 4 6% 8% 41%	5206
April	1st to 10th	Night	3 9% 4 10% 9% 7% 7% 5% 7% 8% 31%	2100
	11th to 20th	Night	8% 11% 3 8% 6% 6% 5% 5% 7% 8% 32%	1835
	21st to end	Night	11% 9% 4 9% 4 5% 6% 4 6% 7% 35%	1680
May	1st to 10th	Night	5% 6% 3 9% 5% 5% 6% 5% 7% 8% 39%	3720
	11th to 20th	Night	7% 8% 3 10% 7% 6% 7% 5% 6% 7% 34%	3013
	21st to end	Night	9% 7% 3 9% 6% 6% 6% 5% 8% 9% 31%	3034
June	1st to 10th	Night	12% 8% 3 8% 6% 6% 6% 4 7% 7% 33%	1200
	11th to 20th	Night	16% 9% 4 9% 7% 4 5% 4 6% 8% 28%	1200
	21st to end	Night	11% 7% 3 7% 6% 4 6% 5% 6% 8% 39%	1200
July	1st to 10th	Night	10% 6% 2 7% 6% 6% 7% 5% 7% 7% 38%	2720
	11th to 20th	Night	9% 6% 2 6% 5% 4 5% 5% 6% 8% 44%	2720
	21st to end	Night	11% 5% 2 6% 4 5% 5% 4 7% 8% 42%	3237
August	1st to 10th	Night	8% 4 2 5% 5% 4 4 4 7% 7% 48%	2537
	11th to 20th	Night	11% 5% 2 6% 5% 4 5% 3 6% 9% 42%	2577
	21st to end	Night	10% 5% 2 6% 5% 5% 6% 4 8% 9% 39%	3133
September	1st to 10th	Night	13% 7% 2 6% 4 4 5% 3 7% 8% 40%	2000
	11th to 20th	Night	11% 6% 3 7% 5% 4 4 4 6% 9% 42%	2000
	21st to end	Night	10% 8% 2 8% 6% 5% 5% 5% 6% 7% 39%	2262
October	1st to 10th	Night	11% 13% 4 9% 5% 5% 5% 4 5% 7% 33%	3920
	11th to 20th	Night	8% 8% 2 7% 5% 6% 6% 4 6% 8% 41%	4105
	21st to end	Night	10% 12% 4 10% 6% 6% 6% 4 6% 7% 31%	4773
November	1st to 10th	Night	13% 13% 5% 10% 5% 4 4 3 6% 8% 29%	2886
	11th to 20th	Night	8% 16% 5% 10% 6% 5% 4 4 5% 7% 29%	3150
	21st to end	Night	6% 14% 5% 12% 8% 5% 5% 4 6% 7% 28%	3281
December	1st to 10th	Night	9% 15% 5% 10% 6% 5% 5% 4 6% 7% 28%	5380
	11th to 20th	Night	8% 16% 5% 12% 9% 7% 5% 4 5% 6% 23%	6090
	21st to end	Night	4 11% 5% 11% 6% 6% 6% 4 7% 8% 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	59% 4 9% 17% 11%	3527
	11th to 20th	Day	50% 3 16% 19% 10% 1	3720
	21st to end	Day	45% 7% 24% 17% 6%	4530
February	1st to 10th	Day	53% 7% 13% 14% 13% 1	1676
	11th to 20th	Day	53% 7% 14% 17% 8% 1	1751
	21st to end	Day	56% 7% 11% 18% 7% 1	1584
March	1st to 10th	Day	53% 4 9% 24% 10%	4618
	11th to 20th	Day	55% 5% 12% 19% 9%	4882
	21st to end	Day	49% 5% 10% 24% 11%	6011
April	1st to 10th	Day	47% 8% 14% 21% 10%	2520
	11th to 20th	Day	50% 6% 13% 19% 11% 1	2731
	21st to end	Day	49% 7% 11% 24% 8% 1	2940
May	1st to 10th	Day	41% 5% 12% 25% 14% 3	6460
	11th to 20th	Day	49% 5% 13% 23% 10% 1	7103
	21st to end	Day	49% 7% 14% 17% 11% 1	8084
June	1st to 10th	Day	46% 8% 12% 22% 10% 1	3201
	11th to 20th	Day	56% 7% 10% 20% 7%	3200
	21st to end	Day	44% 9% 15% 23% 9%	3200
July	1st to 10th	Day	41% 3 17% 20% 18% 1	7161
	11th to 20th	Day	39% 4 16% 29% 11% 1	7153
	21st to end	Day	37% 4 23% 28% 7% 1	7377
August	1st to 10th	Day	36% 5% 16% 34% 9%	4594
	11th to 20th	Day	43% 4 15% 24% 13% 1	4512
	21st to end	Day	40% 6% 25% 24% 5%	4769
September	1st to 10th	Day	40% 6% 22% 27% 5% 1	2400
	11th to 20th	Day	40% 7% 18% 28% 7%	2400
	21st to end	Day	44% 9% 16% 23% 8% 1	2137
October	1st to 10th	Day	51% 4 16% 22% 6% 1	3280
	11th to 20th	Day	48% 4 16% 27% 5%	3046
	21st to end	Day	47% 4 23% 21% 5%	3021
November	1st to 10th	Day	53% 6% 15% 20% 5% 1	1611
	11th to 20th	Day	54% 6% 15% 16% 8%	1470
	21st to end	Day	55% 5% 12% 18% 8% 1	1334
December	1st to 10th	Day	63% 5% 15% 9% 6% 1	2020
	11th to 20th	Day	64% 5% 14% 13% 4	2324
	21st to end	Day	40% 5% 16% 27% 10% 2	3058
January	1st to 10th	Night	60% 4 9% 15% 11% 1	9367
	11th to 20th	Night	47% 4 15% 19% 13% 1	9286
	21st to end	Night	49% 6% 19% 18% 8%	9651
February	1st to 10th	Night	55% 5% 13% 16% 10% 1	2943
	11th to 20th	Night	53% 7% 12% 19% 8% 1	2765
	21st to end	Night	54% 5% 13% 19% 9% 1	2222
March	1st to 10th	Night	50% 4 12% 19% 15% 1	5496
	11th to 20th	Night	53% 7% 12% 19% 10%	5335
	21st to end	Night	39% 6% 10% 26% 18%	5206
April	1st to 10th	Night	47% 6% 14% 21% 11% 1	2100
	11th to 20th	Night	47% 5% 13% 23% 11% 1	1835
	21st to end	Night	46% 7% 10% 26% 10% 1	1680
May	1st to 10th	Night	39% 7% 11% 25% 14% 3	3717
	11th to 20th	Night	45% 5% 12% 26% 10% 1	3013
	21st to end	Night	43% 7% 15% 22% 9% 3	3034
June	1st to 10th	Night	47% 6% 10% 24% 11% 1	1200
	11th to 20th	Night	53% 7% 10% 23% 7% 1	1200
	21st to end	Night	40% 8% 17% 23% 11% 1	1200
July	1st to 10th	Night	44% 4 15% 22% 14%	2690
	11th to 20th	Night	37% 5% 16% 28% 13% 1	2684
	21st to end	Night	38% 5% 21% 28% 8%	3146
August	1st to 10th	Night	34% 7% 18% 32% 10%	2530
	11th to 20th	Night	39% 5% 13% 28% 14% 1	2601
	21st to end	Night	40% 5% 28% 21% 5%	3133
September	1st to 10th	Night	40% 8% 19% 25% 7% 1	2000
	11th to 20th	Night	39% 6% 18% 31% 6%	2000
	21st to end	Night	43% 8% 16% 22% 11% 1	2262
October	1st to 10th	Night	52% 5% 14% 20% 8% 1	3920
	11th to 20th	Night	41% 5% 16% 30% 8%	4105
	21st to end	Night	52% 5% 15% 22% 5%	4773
November	1st to 10th	Night	53% 7% 13% 21% 6% 1	2886
	11th to 20th	Night	55% 6% 12% 18% 8%	3150
	21st to end	Night	54% 6% 12% 20% 7% 1	3281
December	1st to 10th	Night	56% 5% 15% 17% 6% 1	5380
	11th to 20th	Night	62% 5% 14% 13% 5%	6087
	21st to end	Night	48% 5% 15% 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	15% 9% 31% 30% 10% 5%	220
	11th to 20th	Day	15% 16% 31% 25% 10% 1	220
	21st to end	Day	13% 17% 29% 22% 17% 3	242
February	1st to 10th	Day	15% 10% 30% 25% 15% 4	220
	11th to 20th	Day	13% 15% 27% 26% 16% 3	323
	21st to end	Day	12% 15% 37% 25% 10% 1	370
March	1st to 10th	Day	11% 17% 28% 26% 13% 4	540
	11th to 20th	Day	12% 14% 34% 25% 12% 2	540
	21st to end	Day	17% 15% 29% 25% 13% 2	594
April	1st to 10th	Day	12% 17% 35% 24% 11% 2	540
	11th to 20th	Day	15% 19% 27% 25% 11% 4	532
	21st to end	Day	15% 18% 31% 21% 13% 3	540
May	1st to 10th	Day	16% 17% 33% 24% 8% 2	543
	11th to 20th	Day	14% 11% 24% 28% 18% 4	858
	21st to end	Day	15% 13% 24% 29% 16% 3	1072
June	1st to 10th	Day	15% 16% 32% 22% 13% 2	931
	11th to 20th	Day	21% 11% 24% 24% 16% 4	930
	21st to end	Day	14% 9% 24% 25% 21% 7%	930
July	1st to 10th	Day	15% 9% 25% 27% 21% 4	916
	11th to 20th	Day	13% 9% 26% 26% 20% 6%	912
	21st to end	Day	12% 10% 27% 29% 16% 6%	892
August	1st to 10th	Day	13% 12% 19% 29% 19% 7%	573
	11th to 20th	Day	15% 15% 28% 23% 15% 5%	517
	21st to end	Day	14% 14% 28% 20% 15% 8%	583
September	1st to 10th	Day	17% 11% 27% 20% 18% 7%	530
	11th to 20th	Day	17% 12% 28% 25% 12% 5%	530
	21st to end	Day	14% 26% 29% 21% 10% 1	530
October	1st to 10th	Day	25% 15% 28% 19% 10% 3	530
	11th to 20th	Day	17% 15% 34% 23% 11% 1	405
	21st to end	Day	19% 14% 28% 24% 11% 3	305
November	1st to 10th	Day	20% 14% 29% 25% 10% 2	220
	11th to 20th	Day	21% 15% 30% 25% 8% 2	220
	21st to end	Day	19% 16% 26% 24% 11% 4	220
December	1st to 10th	Day	15% 20% 27% 26% 9% 3	220
	11th to 20th	Day	17% 13% 20% 34% 16%	220
	21st to end	Day	11% 12% 25% 30% 18% 5%	242
January	1st to 10th	Night	13% 10% 28% 32% 13% 2	1160
	11th to 20th	Night	13% 17% 26% 31% 11% 1	1117
	21st to end	Night	19% 18% 29% 25% 9%	1045
February	1st to 10th	Night	15% 13% 22% 28% 18% 4	841
	11th to 20th	Night	12% 13% 28% 31% 14% 2	824
	21st to end	Night	8% 12% 32% 29% 16% 3	692
March	1st to 10th	Night	9% 12% 27% 32% 17% 3	840
	11th to 20th	Night	12% 9% 30% 32% 14% 2	840
	21st to end	Night	12% 9% 24% 32% 20% 3	924
April	1st to 10th	Night	8% 10% 29% 33% 18% 3	840
	11th to 20th	Night	12% 11% 30% 30% 14% 3	587
	21st to end	Night	15% 13% 28% 28% 15% 1	420
May	1st to 10th	Night	11% 14% 27% 33% 13% 2	420
	11th to 20th	Night	12% 9% 25% 32% 20% 2	414
	21st to end	Night	15% 9% 24% 29% 20% 2	455
June	1st to 10th	Night	13% 9% 28% 31% 17% 2	400
	11th to 20th	Night	21% 6% 22% 31% 18% 3	400
	21st to end	Night	15% 6% 22% 34% 21% 2	400
July	1st to 10th	Night	14% 6% 21% 35% 23% 1	390
	11th to 20th	Night	13% 6% 25% 30% 22% 5%	388
	21st to end	Night	10% 6% 23% 36% 21% 4	438
August	1st to 10th	Night	10% 5% 19% 33% 29% 6%	398
	11th to 20th	Night	10% 10% 26% 32% 20% 2	396
	21st to end	Night	13% 6% 27% 31% 21% 2	587
September	1st to 10th	Night	17% 9% 20% 36% 17% 3	800
	11th to 20th	Night	15% 7% 23% 32% 21% 3	800
	21st to end	Night	15% 19% 28% 26% 10% 2	800
October	1st to 10th	Night	19% 13% 26% 29% 12% 1	800
	11th to 20th	Night	16% 14% 31% 28% 11% 1	800
	21st to end	Night	21% 14% 31% 25% 7% 1	880
November	1st to 10th	Night	19% 13% 29% 25% 13% 2	836
	11th to 20th	Night	16% 16% 31% 28% 8% 1	1050
	21st to end	Night	15% 15% 31% 28% 10% 1	1119
December	1st to 10th	Night	15% 14% 32% 29% 10% 1	1160
	11th to 20th	Night	15% 14% 28% 28% 13% 2	1160
	21st to end	Night	13% 11% 26% 34% 14% 2	1276

Page generated at 2026-05-28 23:53:30. Version ac07

Copyright © 2026 Attilla Danko.