May 2015 Summary – 4º Warmer than Normal – Warm and Dry Outlook


After what was a strangely normal April… we went back to a regime of consistent above average temperatures in May.  High temperatures were more than 4ºC above normal for our highs and 3ºC above normal for our lows.  Despite the well above normal temperatures we only managed to set 4 new record high temperatures at the Airport, and none of them were all time records for the day according to the long-period stations in the Valley.

In previous years, a dry and warm May might have meant a big freshet as the streams filled with snow runoff. So really what set this May apart was, again, the lack of snow on the mountains to contribute to our rivers and streams.  Anecdotally, our local lakes including Sproat, Great Central, Stamp and others are all at “August lows”.  Looking at the mountains, Mt. Arrowsmith looks like it might on September 1st rather than June 1st.  And Mt. Kiltsa, which often has snow on its upper reaches through the summer and fall… is nearly bare as well.


Fire Danger on High – Expect Extreme by mid-to-late June.


The concern going forward will be fire.  We are currently at a High fire danger rating.  An open burning ban is now in effect inside and outside of the City and if the dry weather continues I would expect us to get to an Extreme danger rating near the middle to end of June.

Rainfall measurements improve at Airport

After months with only a few days of reported precipitation, it appears that perhaps something has been fixed at the Airport.  This months report “only” omits the first 5 days of rain (which of course were the ones with the most precipitation at other stations).  I am hopeful that the consistency will hold through the summer and especially fall.  We might not have much to measure this summer, but surely we will want to catch that first rainfall in the autumn so we can get a good idea of when our dry season is over.  You never know, we might also get the odd thundershower induced downpour in August or September like we did last year.  No matter what, we need that official station to function properly.

El Niño update

The latest El Niño forecast was released May 14th. The new one will not be released until the middle of this month.  I’ll post the June update in the June Summary.  The main synopsis  of the latest one is:

There is an approximately 90% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 80% chance it will last through 2015…. 

…. Collectively, these features reflect weak to moderate strength El Niño conditions.


Outlooks — Spring and Summer looking warm and dry.

Here is a new feature for this summary.  The current 15 day outlook from the super-long range ensemble model from Environment Canada available at  The outliers are pretty high, but the mean forecast is less than 20mm of rain over the next 15 days, and the majority of that in the very short term which other models disagree with and none again until the final few days of the forecast which are the most unsure.  Basically, after Tuesday it forecasts a full week and up to two weeks of no-rain.  This is unusual for June.

Screen Shot 2015-06-01 at 11.02.25 AM

I have not updated the rest of the long term forecasts since I just compiled them a couple weeks ago and they have not yet updated.  But the reminder is that it is expected to be hot and dry all summer.

The NMME outlooks are available here.  Outlook for Temperature, Precipitation and Sea Surface Temperature for June, July, August (JJA):
2ºC Above Normal and Drier than normal.
(compared to last months prediction, warm and dry conditions predicted over broader section of Western Canada)



Below is the Sea Surface Anomaly map.  I have retained last months prediction for the MJJ time period on the bottom.  Notice the later period shows significantly more warmth in the El Niño rectangular box along the Equator.  The persistent and abnormal warm water along the entire West Coast of the Americas is quite something, but especially the Northern portions.

Outlook for Temperature Precipitation and Sea Surface Temperature  for July, August, September (JAS):
2ºC Above Normal and drier than normal.


Here are the probabilities (the confidence levels) for those forecasts.

It all looks nothing but hot and dry.

That’s it!  Check the data for the month is below!

Daily records set this month at the Airport (and compared to other stations* for “All Time”)

Four new Airport highs, none all-time.

  • May 8 high 25.7º C : #1 is 31.5º C in 1987 at Robertson Creek.
  • May 19 high 27.1º C: #1 is 30.0º C in 1928 at Beaver Creek. 
  • May 20 high 28.8º C: #1 is 32.8º C in 1963 at Robertson Creek.
  • May 21 high 29.8º C: #1 is 33.9º C in 1963 at Robertson Creek.
  • May 29 high 27.5º C: #1 is 34.5º C in 1983 at Robertson Creek.

*Short Term Airport Records are compared to the 30+ year weather stations of record since 1900 at Beaver Creek, Port Alberni City and Robertson Creek.

May 2015  Minimum, Overall and High Daily Average Temps See last month’s and last May’s summary.

Alberniweather: 9.6º C, 15.4° C, 22.7º C
Alberni Elementary School : 9.4º C, 15.2º C, 22.6° C
Maquinna Elementary School9.2º C, 14.9º C, 22.6° C
Neptune Canada Station: Incomplete
Overall City Average: 9.4º C, 15.17 C, 22.63º C
Environment Canada Airport7.3º C, 15.2° C, 23.0º C

1981-2010 Env Can Normal (Rbrtsn Creek): 6.0º C, 12.3º C, 18.6° C

Precipitation for May 2015:

Alberniweather: 6.6 mm
AES: 9.0 mm
MAQ: 8.8 mm
NEP: NA (not measured)
Overall City Average: 8.13 mm
EC: 1.4mm (missed 4th and 5th which were largest rainfall of month)

1981-2010 Env Canada Normal (Robertson Creek): 87.8 mm

City Stations Temperature Difference from normal:
+3.4° C, +2.87º C, +4.03º C
Official (Airport) Temperature Difference from normal:
 +1.3º C, +2.9º C, +4.4º C
City Stations Precipitation difference normal:
 -79.67 mm (9.3% of normal)
Official (Airport) Precipitation difference from  normal:
—- missing key days

*Denotes incomplete data for the month

Comparison to recent Mays at Alberniweather (unless specified)

  • 2014: See the May 2014 Summary Here. Significantly warmer this (2015) year with less rain.
  • 2013: See the May 2013 Summary Here. Significantly warmer this (2015) year with less rain.
  • 2012: Cooler than 2015 but fairly dry.
  • 2011: Cool and near normal rain compared to this (2015) year.
  • 2010: 2010 was very cool (our mean average was the same as that months mean high!) and 2010 had normal rain.
  • 2009: Significantly warmer this year with less rain.
  • 2008: Significantly warmer this year with a bit less rain.
  • 2007: Significantly warmer this year with less rain.
  • 2006:  Significantly warmer this year with less rain.

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1 thought on “May 2015 Summary – 4º Warmer than Normal – Warm and Dry Outlook

  1. Great summary Chris! I’ve never seen another May like this, and the summer looks like more of the same. Pretty remarkable.

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